Hi, I see you have Flashblock, Yahoo Mail Button and Yahoo Toolbar extensions. Try temporarily disabling those - in particular Flashblock, to see if one of them is causing the problem. Also try Adblock Plus - although that is less likely.

If it isn't your extensions, click the icon (globe or padlock) at the left-hand end of the address bar - the Site Identity button, > More information > Permissions tab, and make sure Flash isn't set to 'Block.'

Hope that helps.

Security Issue: Update your Flash Player v16.0.0.296
https://www.adobe.com/products/flashplayer/distribution3.html

Some added toolbar and anti-virus add-ons are known to cause Firefox issues. Disable All of them.

Start Firefox in Safe Mode {web link} While you are in safe mode;

Type about:preferences#advanced<Enter> in the address bar.

Under Advanced, Select General. Look for and turn off Use Hardware Acceleration.

Poke around safe web sites. Are there any problems?