Update Firefox: Click the menu button New Fx Menu , click help Help-29 and select About Firefox. See Update Firefox to the latest version for details.

   Update your plugins: Go to our Plugin Check page and follow the links to update any plugins that are out of date.
   Update Windows: Make sure you have all of the latest security and stability fixes. Go to the Start menu, select All Programs and then Windows Update.
   Update your drivers: Check your printer driver and graphics drivers are up-to-date. For more info, see Upgrade your graphics drivers to use hardware acceleration and WebGL.
   Update your Internet Security software: Make sure you have the latest version of your Internet security software (including firewalls, antivirus programs, anti-spyware programs, and more).

hope that was useful else....try to Check for viruses or spyware...troubleshoot...