What anti-virus do you have enabled? Have you tried with a new profile? Profile Manager - Create, remove or switch Firefox profiles

I don´t have any anti-virus, what i know. My previus isp had a great firewall and anti-virus so i didne´t have the need for it.

You should have an anti-virus (McAffee, AVG, Norton, etc.), it's important to always have one installed. If you don't have one on your computer, do the following:

Scan for Malware

Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try some of the following programs to scan for malware:

• MalwareBytes' Anti-Malware
• TDSSKiller - AntiRootkit Utility
• Microsoft Security Essentials (Keep this as your anti-virus, it's free)

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Reset Firefox

The Reset Firefox feature can fix many issues by restoring Firefox to its factory default state while saving your essential information. Note: This will cause you to lose any Extensions, Open websites, and some Preferences.

To Reset Firefox do the following:

1. Go to Firefox > Help > Troubleshooting Information.
2. Click the "Reset Firefox" button.
3. Firefox will close and reset. After Firefox is done, it will show a window with the information that is imported. Click Finish.
4. Firefox will open with all factory defaults applied.

Further information can be found in the Refresh Firefox - reset add-ons and settings article.

Did this fix your problems? Please report back to us!

Such issues can also be caused by F-Secure Browser Protection

• http://community.f-secure.com/t5/Protection-Safe/Browser-Protection-is-making/td-p/2355/page/6

Try to disable "Use advanced process monitoring" in the F-Secure Deepguard settings.

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 helps.

• http://windows.microsoft.com/en-US/windows7/Advanced-startup-options-including-safe-mode
• http://windows.microsoft.com/en-US/windows-vista/Advanced-startup-options-including-safe-mode