Could you try disabling graphics hardware acceleration? Since this feature was added to Firefox, it has gradually improved, but there still are a few glitches.

You might need to restart Firefox in order for this to take effect, so save all work first (e.g., mail you are composing, online documents you're editing, etc.). Then perform these steps:

• Click the orange Firefox button at the top left, then select the "Options" button, or, if there is no Firefox button at the top, go to Tools > Options.
• In the Firefox options window click the Advanced tab, then select "General".
• In the settings list, you should find the Use hardware acceleration when available checkbox. Uncheck this checkbox.
• Now, restart Firefox and see if the problems persist.

Additionally, please check for updates for your graphics driver by following the steps mentioned in the following Knowledge base articles:

Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Upgrade your graphics drivers to use hardware acceleration and WebGL

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

Did you check that your security software (firewall, anti-virus) isn't blocking Firefox?

my firewall antivirus is not blocking anything. 17.0.1 runs smoothly without any problem. i tried to disable the hardware graphics acceleration as well then browser based apps. totally stopped responding like king's bounty legions which needs hardware acceleration. however 17.0.1 runs perfectly with hardware acceleration. why should i disable it? i also tried 19.0 beta version as well same problem there. i checked beta versions of 17.0 and they work perfectly too. what ever done with 18.0 just passed to 19.. and other beta versions..

Try to disable IPv6.

• http://kb.mozillazine.org/Error_loading_websites#IPv6