First, could you try Firefox's Safe Mode, which is a standard diagnostic for interference by add-ons?

First, I recommend backing up your Firefox settings in case something goes wrong. See Back up and restore information in Firefox profiles. (You can copy your entire Firefox profile folder somewhere outside of the Mozilla folder.)

Next, restart Firefox in Firefox's Safe Mode (Diagnose Firefox issues using Troubleshoot Mode) using

Help > Restart with Add-ons Disabled

In the Safe Mode dialog, do not check any boxes, just click "Continue in Safe Mode."

If searches work correctly, this points to one of your add-ons or custom settings as the problem.

Any change?

Do a malware check with some malware scanning programs on the Windows computer.
You need to scan with all programs because each program detects different malware.
Make sure that you update each program to get the latest version of their databases before doing a scan.

• http://www.malwarebytes.org/mbam.php - Malwarebytes' Anti-Malware
• http://www.superantispyware.com/ - SuperAntispyware
• http://www.microsoft.com/security/scanner/en-us/default.aspx - Microsoft Safety Scanner
• http://www.microsoft.com/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page
• http://www.safer-networking.org/en/index.html - Spybot Search & Destroy

You can also do a check for a rootkit infection with TDSSKiller.

• http://support.kaspersky.com/viruses/solutions?qid=208280684

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked

I'm afraid I did not realize the magnitude of this Problem.

This is actually a virus/malware/ROOTKIT!!! that is currently beginning to infect Mozilla Firefox and Windows users...it is not currently detected by ANY of the virus/malware removers mentioned at this time. However, you can look all over the Internet & see people who are just starting to be infected by the Rootkit. It will randomly divert webpages & google searches to various websites...and gradually deteriorate your system performance until it will not run any more. You can read about it on any of the major Antivirus companies websites. I am a "paranoid" user that runs ALL of the major, well-established Antispyware/Malware programs completely on all my systems every couple of weeks, have a Pro Firewall, and do not do any things I should not be doing on the Internet. This is a really nasty virus, and I guarantee some of you will get it at some point in the future. Look out, and do your research before it strikes, cause it is difficult, if not Totally Impossible even for an "Expert" to remove

did I mention it completely disables report a web forgery, in firefox?

Did you try TDSSkiller?

If you want to post some links to security company pages, that would be great. Otherwise, it will be hard to find the right malware.

Check you system with Oshi Unhooker (http://www.oshiunhooker.com), it is free. If after you scanned and cleared all founding problem disappear - it means you had some spyware.