I cannot open a New Window. How do I get the ability to open a new (second) window?

Question

When I upgraded from 3.6.15 to 3.6.18 it wiped out the use of all my extensions, add ons, and bookmarks, yet they were all still there. I deleted the suffixes on extensions, rebooted FF and they all started working. The only thing not working is opening a New Window. I click on File - New Window, I right click on FF icon on desktop, icon in Quick menu, I tried dragging a tab to the desktop. Nothing works.
Also FF will not allow me to install the update Adobe plugin.

Answer 1

-> Tap ALT key or press F10 to show the Menu Bar
-> go to Help Menu -> select "Restart with Add-ons Disabled"
Firefox will close then it will open up with just basic Firefox. Now do this:
-> Update ALL your Firefox Plug-ins https://www.mozilla.com/en-US/plugincheck/
-> go to View Menu -> Toolbars -> unselect All Unwanted toolbars
-> go Tools Menu -> Clear Recent History -> '''Time range to clear: select EVERYTHING''' -> click Details (small arrow) button -> place Checkmarks on '''Cookies, Cache, Site Preferences''' -> click "Clear Now"
-> go to Tools Menu -> Options -> Content -> place Checkmarks on:
1) Block Pop-up windows 2) Load images automatically 3) Enable JavaScript
-> go to Tools Menu -> Options -> Privacy -> History section -> '''Firefox will: select "Use Custom Settings for History"''' -> REMOVE Checkmark from '''"Permanent Private Browsing mode"''' -> place CHECKMARKS on:
1) Remember my Browsing History 2) Remember Download History 3) Remember Search History 4) Accept Cookies from sites -> select "Exceptions..." button -> Click "Remove All Sites" at the bottom of "Exception - Cookies" window
4a) Accept Third-party Cookies -> under "Keep Until" select "They Expire"
-> REMOVE CHECKMARK from CLEAR HISTORY WHEN FIREFOX CLOSES
-> When using the Location Bar, suggest: select "History and Bookmarks"
-> go to Tools Menu -> Options -> Security -> place Checkmarks on:
1) Warn me when sites try to install add-ons 2) Block reported attack sites 3) Block reported web forgeries 4) Remember Passwords for sites
-> Click OK on Options window
-> click the Favicon (small drop down menu icon) on Firefox SearchBar (its position is on the Right side of the Address Bar) -> click "Manage Search Engines" -> select all Unwanted Search Engines and click Remove -> click OK
-> go to Tools Menu -> Add-ons -> Extensions section -> REMOVE All Unwanted/Suspicious Extensions (Add-ons) -> Restart Firefox
You can enable your Known & Trustworthy Add-ons later. Check and tell if its working.