First, try to reset Firefox. [[Reset Firefox – easily fix most problems]]. This simple step will eliminate many Firefox problems with only one click. A few other basic trouble shooting things you can try is this: Run all Windows Updates, install all needed service packs, etc. Update your graphics driver (Firefox uses your graphics card for some rendering, and an out of date graphics card driver can cause problems. [[Upgrade your graphics drivers to use hardware acceleration and WebGL]] Update all your plugins (Flash, Java, etc.): [http://www.mozilla.org/plugincheck/ http://www.mozilla.org/plugincheck/]. Download and Install MalwareBytes Anti-Malware, run a full Scan. [http://www.malwarebytes.org/ http://www.malwarebytes.org/]. This helps check that there are no viruses on your computer causing issues. You can uninstall this program after you clean off any infections.

I updated the plugins first and that did it immediately after rebooting.

Brilliant answer. I updated the plugins first and that did it immediately after rebooting. Thanks very much for your help