Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

Hi Cor-el,

Thanks for your reply.

I did that ant the issue gone now i dont know which addon cased the issue.

This from the troubleshooting page. https://drive.google.com/file/d/0B1ImGxntnczbblc2VVZUS1E3Nkk/view?usp=sharing

Thanks

Could you check the list again in "normal" mode? You probably do not have all of those extensions enabled and it would help narrow down the list...

Does the problem affect only the first window you open, or all windows?

How to do that?

I'm using one window with many tabs and the issue happens randomly in the first window.

Thanks