I can't do anything with Firefox

Question

My browser used to work just fine, but today I opened it and this is what it looked like:
http://i49.tinypic.com/mbprbr.png
As you can see there are no toolbars except for the bookmarks one and the page is black. Same goes for new windows, and when I right-click the nonexistent toolbars a completely black menu appears (it looks just like the pages).
The same thing happens even when I try Safe Mode, and I did a clean reinstall but it didn't help.

Answer 1

Do a clean reinstall and delete the Firefox program folder (C:\Program Files\Mozilla Firefox\) before reinstalling a fresh copy of Firefox.
Download a fresh Firefox copy and save the file to the desktop.
*Firefox 15.0.x: http://www.mozilla.org/en-US/firefox/all.html
Uninstall your current Firefox version, if possible, to cleanup the Windows registry and settings in security software.
*Do NOT remove personal data when you uninstall your current Firefox version, because all profile folders will be removed and you will also lose your personal data like bookmarks and passwords from profiles of other Firefox versions.
Remove the Firefox program folder before installing that newly downloaded copy of the Firefox installer.
*It is important to delete the Firefox program folder to remove all the files and make sure that there are no problems with files that were leftover after uninstalling.
*http://kb.mozillazine.org/Uninstalling_Firefox
Your bookmarks and other profile data are stored in the Firefox Profile Folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected when you uninstall Firefox.
If you keep having problems then also create a new profile.
You can also try to boot the computer in Windows Safe mode with network support (press F8 on the boot screen) as a test to see if that works.
*http://kb.mozillazine.org/Profile_folder_-_Firefox
*http://kb.mozillazine.org/Profile_backup
*http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Clean_reinstall