Firefox doesn't open, but is open in Processes in Task Manager, not even profile manager opens up for Firefox opens up. Please help

Question

I'm using Vista, 32 bit - not even downloading the beta version of Firefox 4 helps; it downloads (just like the regular version of Firefox, 3.4) and I can install it, but trying to run it gives me nothing - no warning, no text; it just doesn't open up, but is still visible in my start menu, programs folder and in task manager. And not even profile manager opens up.

Answer 1

Make sure that you do not remove your personal data when you uninstall Firefox. Then you won't lose personal data stored in a different location in the [http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder].
See also http://kb.mozillazine.org/Profile_backup and [[Backing up your information]]
A possible cause is security software (firewall) that blocks Firefox.<br />
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.<br />
See [[Server not found]] and [[Firewalls]] and http://kb.mozillazine.org/Firewalls
See also http://kb.mozillazine.org/Browser_will_not_start_up
Do a malware check with a few malware scan programs.<br />
You need to use all programs because each detects different malware.<br />
Make sure that you update each program to get the latest version of the database.<br />
*http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
*http://www.superantispyware.com/ - SuperAntispyware
*http://www.safer-networking.org/en/index.html - Spybot Search & Destroy
*http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free
*http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page
See also "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked and [[Searches are redirected to another site]]