Downloaded 9.0.1 firefox will not open

Downloaded Version 9.0.1 to replace 7.0.1 and when I attempted to open Firefox, the following error message came up:
This application has failed to start because MOZCRT19.dll was not found. Re-installing application may fix problem.
Re-installed - no help, Microsoft internet search for fix - no help

Hi,
I think MOZCRT19.dll is not used anymore and it doesn't come with the latest Firefox installer. Please try uninstalling Firefox and delete the Firefox installation folder '''Computer > ?\Program Files\Mozilla Firefox''' or '''Computer > ?\Program Files (x86)\Mozilla Firefox''' before installing the new one. When uninstalling do not enable the option to delete profile and preferences. You may also want to take a backup of your [http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder & Files] which is separate from the installation folder and stores bookmarks, passwords etc.
https://www.mozilla.org/en-US/firefox/new/
Useful links:
[https://support.mozilla.com/en-US/kb/Options%20window All about Tools > Options]
[http://kb.mozillazine.org/About:config Going beyond Tools > Options - about:config]
[http://kb.mozillazine.org/About:config_entries about:config Entries]
[https://support.mozilla.com/en-US/kb/Page%20Info%20window Page Info] Tools (Alt + T) > Page Info, Right-click > View Page Info
[https://support.mozilla.com/en-US/kb/Keyboard%20shortcuts Keyboard Shortcuts]
[https://support.mozilla.com/en-US/kb/Viewing%20video%20in%20Firefox%20without%20a%20plugin Viewing Video without Plugins]
[http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder & Files]
[https://developer.mozilla.org/en/Command_Line_Options#Browser Firefox Commands]
[https://support.mozilla.com/en-US/kb/Basic%20Troubleshooting Basic Troubleshooting]
[https://support.mozilla.com/en-US/kb/common-questions-after-upgrading-firefox-36 After Upgrading]
[https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode]
[http://kb.mozillazine.org/Problematic_extensions Problematic Extensions]
[https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes Troubleshooting Extensions and Themes]
[https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins Troubleshooting Plugins]
[http://kb.mozillazine.org/Testing_plugins Testing Plugins]

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You may need to delete the Firefox program folder before (re)installing the latest Firefox. 
In case you still have problems after installing then check your security software.
A possible cause is security software (firewall) that blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program.
Remove all rules for Firefox from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process.
See:
*https://support.mozilla.org/kb/Server+not+found
*https://support.mozilla.org/kb/Firewalls
*http://kb.mozillazine.org/Browser_will_not_start_up

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Did you check your security software (firewall)?
A possible cause is security software (firewall) that blocks or restricts Firefox without informing you about that, possibly after detecting changes (update) to the Firefox program.
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If necessary then also see:
* http://kb.mozillazine.org/Browser_will_not_start_up
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*https://support.mozilla.org/kb/Server+not+found
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*http://kb.mozillazine.org/Profile_folder_-_Firefox
*http://kb.mozillazine.org/Profile_backup
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was Ok till recently

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Your question title says "Firefox will not open or won't start (see /questions/964132 )" I looked at that question and it was started by another Firefox user. [/questions/964132?page=2#answer-477049] has a number of suggestions if Firefox won't start. Which ones did you try?
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* [[Basic Troubleshooting]]
* http://kb.mozillazine.org/Browser_will_not_start_up
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Certain Firefox problems can be solved by performing a ''Clean reinstall''. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:
'''Note:''' You might want to print these steps or view them in another browser.
#Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
#After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
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#*'''Windows:'''
#**C:\Program Files\Mozilla Firefox
#**C:\Program Files (x86)\Mozilla Firefox
#*'''Mac:''' Delete Firefox from the Applications folder.
#*'''Linux:''' If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see [[Installing Firefox on Linux]]. If you downloaded and installed the binary package from the [http://www.mozilla.org/firefox#desktop Firefox download page], simply remove the folder ''firefox'' in your home directory.
#Now, go ahead and reinstall Firefox:
##Double-click the downloaded installation file and go through the steps of the installation wizard.
##Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.
Please report back soon.

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Every time Firefox opened
== User Agent ==
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; Trident/4.0; GTB0.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C)

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Your plugins list shows outdated plugin(s) with known security and stability risks.
* Shockwave Flash 10.0 r45
* Java Plug-in 1.6.0_05 for Netscape Navigator (DLL Helper)
Update the [[Java]] plugin to the latest version.
*http://java.sun.com/javase/downloads/index.jsp (Java Platform: Download JRE)
Update the [[Flash]] plugin to the latest version.
*http://www.adobe.com/software/flash/about/

Firefox will not open...please help.

My Mozilla Firefox will not open any windows, although it does start and show as running in my task manager. I have uninstalled and reinstalled it twice now and restarted my computer twice.
I CANNOT start Firefox in safe mode by holding down shift or using the "firefox/safe" in the run box.
I've tried it with applications closed, and open....I've tried it online and offline, I tried to run it in compatibility mode, I checked my computer for viruses...nothing helps.
I have read every troubleshooting item here but they only say try safe mode, or do something from Firefox when it is open such as reset it. I have no add-ons or extensions on Firefox and it just worked yesterday...also my computer is brand new Windows 8.1 12GB ram 2TB harddrive and everything else works fine.
please help

Hello,
Certain Firefox problems can be solved by performing a ''Clean reinstall''. This means you remove Firefox program files and then reinstall Firefox. Please follow these steps:
'''Note:''' You might want to print these steps or view them in another browser.
#Download the latest Desktop version of Firefox from http://www.mozilla.org and save the setup file to your computer.
#After the download finishes, close all Firefox windows (click Exit from the Firefox or File menu).
#Delete the Firefox installation folder, which is located in one of these locations, by default:
#*'''Windows:'''
#**C:\Program Files\Mozilla Firefox
#**C:\Program Files (x86)\Mozilla Firefox
#*'''Mac:''' Delete Firefox from the Applications folder.
#*'''Linux:''' If you installed Firefox with the distro-based package manager, you should use the same way to uninstall it - see [[Installing Firefox on Linux]]. If you downloaded and installed the binary package from the [http://www.mozilla.org/firefox#desktop Firefox download page], simply remove the folder ''firefox'' in your home directory.
#Now, go ahead and reinstall Firefox:
##Double-click the downloaded installation file and go through the steps of the installation wizard.
##Once the wizard is finished, choose to directly open Firefox after clicking the Finish button.
Please report back to see if this helped you!
Thank you.

WARNING: Do not run Firefox's uninstaller or use a third party remover as part of this process, because that could permanently delete your Firefox data, including but not limited to, extensions, cache, cookies, bookmarks, personal settings and saved passwords. These cannot be recovered unless they have been backed up to an external device!

Firefox will not open, it gives me this cod and would not turn off, Error on switching in renew: NS_ERROR_UNEXPECTED, Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIPrefBranch.getCharPref] id: none

I restored my computer to earlier time and I did an other restore but to latest time and since then every time I click on Firefox short cut this window comes up with the same cod and I can not turn it off unless turn off or restart my laptop, I did delete the Firefox few times and reinstalled it but did not change anything, still I get the same cod,
Error on switching in renew:
NS_ERROR_UNEXPECTED, Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIPrefBranch.getCharPref]
id: none

Some how I solved my problem by opening a user account and downloading Firefox 4.0 beta and installing it, I did try it, worked fine, so I did close the user account and did go back to my own account(switched user), the main page that I had problem with Firefox which would not open, I dabble click on Firefox it start working again!! I hope that solves your problem too.
firefox will not open, it gives me this cod and would not turn off, Error on switching in renew: NS_ERROR_UNEXPECTED, Component returned failure code: 0x8000ffff (NS_ERROR_UNEXPECTED) [nsIPrefBranch.getCharPref] id: none

I upgraded from 3.6.13 to Beta 4.0 and now Firefox will not open at all I tried to uninstall to start again but it will not uninstall either it does nothing.

I uninstalled Beta 4 and re-installed 3.6.13 now Firefox will not open at all I tried to uninstall to start again but it will not uninstall either it does nothing, I have been using Firefox for a long time but cannot resolve this problem can anyone help and give me a solution please. As I use Firefox as my web browser it is very frustrating.
The fact it will not uninstall appears to be something completely new as nobody I know who uses Firefox has ever encountered this in the past.

Did you check your security software (firewall)?
A possible cause is security software (firewall) that blocks or restricts Firefox without informing you about that, possibly after detecting changes (update) to the Firefox program.
Remove all rules for Firefox from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process.
See [[Server not found]] and [[Firewalls]] and http://kb.mozillazine.org/Firewalls
If necessary then also see:
* http://kb.mozillazine.org/Browser_will_not_start_up
* http://kb.mozillazine.org/Error_loading_websites

Downloaded 9.0.1 firefox will not open

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