Bug reports linked to this crash report indicate that it can be caused by malware.

Do a malware check with some malware scanning programs.
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/windows/products/winfamily/defender/default.mspx - Windows Defender: Home Page
• http://www.safer-networking.org/en/index.html - Spybot Search & Destroy
• http://www.lavasoft.com/products/ad_aware_free.php - Ad-Aware Free

See also:

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

i completely uninstalled firefox ( including all personal settings ) and reinstalled it from scratch and it works now

You're welcome

Can you tell use the cause of the problems and how you fixed it?

It helps other who read this thread.

Good to hear about it

i completely uninstalled firefox ( including all personal settings ) and reinstalled it from scratch and it works now