Do a malware check with some malware scanning programs on the Windows computer.
Please 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.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender: Home Page:
  http://www.microsoft.com/windows/products/winfamily/defender/default.mspx
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

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

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

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

If using various malware scanners does not fix it or if you are blocked from installing those scanners then ask advice at a forum that specializes in malware removal.

• http://forums.majorgeeks.com/index.php - MajorGeeks Support Forums
• http://www.security-forums.com/index.php - WindowSecurity.com Security Forums
• http://www.bleepingcomputer.com/forums - Bleeping Computer Forums

HI,

Thanks for your reply..

I have used many of the above applications to clean my PC but no Use.. I also tried Firefox 3.6 and getting the same problem. I Disable all Addons but the same problem. It keeps opening a New Window after every 20 seconds making it impossible to work on Firefox.

Now I am trying uninstalling One by One all the other Programmes/ Applications Every Day and will check if any of the installed Application is causing problem.

Thanks.

As a test of how Firefox runs "uncustomized," could you create a new Firefox profile? In addition to bypassing current add-ons and custom settings, it should have completely fresh settings databases and a fresh cache folder.

Exit Firefox and start up in the Profile Manager as described in this article:

Profile Manager - Create, remove or switch Firefox profiles

Any time you want to switch profiles, exit Firefox and return to that dialog.

When creating a new profile, to avoid data loss, I recommend using the default location suggested, and not re-using any existing folder. Also, even if you don't think you need an old/spare profile and are ready to delete it, I suggest making a backup of your profiles first, in case something goes wrong.

Does the new profile exhibit the same bad behavior?

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test to see if that helps.

It looks like a malware...

If the problem persist the faster solution is to restore windows to a previous point. Before this you should save all the important documents to a external drive.