This appears to be a bug in Bitdefender. Bug 530074

Try to Reset Firefox, ans see if that helps Refresh Firefox - reset add-ons and settings

Additionally, you can try to fully trust Firefox in Bitdefender.. You may have to do it in more than one place or configuration module. Please see this for common configuration instructions.

AV/Firewall Configuration

Support

Thank u for reply, i checked BD firewall rules& everything seems to be OK. There may have some problem in BD&FF.

@Tylerdowner I've just had fresh install, is resetting will help it  ?

You can safely try the Reset feature to check if a problematic add-on is causing conflicts. To revert back, middle-click the Firefox taskbar icon to open the Firefox Profile Manager and choose Default User. You can also delete the profile created by the reset feature (the one containing random numbers).

Profile Manager

Profile Howto

nothing better after the reset :( then i tried to use without any addons, it is still same

Hi ,

   I encountered the same problem using bitdefender 2013 TS, i just reinstalled FF14 with the exe file from mozilla website. The crashing has stopped, hope it stays this way.

Try reinstalling FF14 again, and hope it stops crashing, good luck.

I bought and installed Bitdefender antivirus plus 2013 having used McAfee for 15 years, a big mistake. Bitdefender software is full of bugs which manifest themselves across a number of browsers. I have since purged it from my PC and returned to McAfee.

I have 4 browsers installed and can confidently confirm that Bitdefender is not compatible with my favourite browser, Firefox 15. Even with antiphising disabled it screws Firefox up repeatedly freezing screens, particularly on Flash videos, and in most cases requiring a Task Master process to terminate Firefox, or worse still a reboot if Firefox goes into Safe Mode when restarted.

Quick test: Load "The Beatles - Abbey Road - YouTube" switch back and forwards between the standard screen and full screen at a normal rate, occasionally changing the time scrollbar, and when on the standard screen scroll it up and down. Guaranteed to freeze.

The Bitdefender product is nowhere remotely intuitive and the Help File is woefully lacking in content. Bitdefender support is next to non-existent, they just ignore requests for assistance, possibly hoping you will just give up and blame someone else like Firefox or Adobe. They have obviously not tested their product with a range of browsers and the most commonly used add-ons.

It is not up to Firefox or Adobe to make their software work with an antivirus product, quite the contrary; and I know of at least one that works perfectly.

My advice is do not use Bitdefender if you want troublefree browsing with Firefox.