Start Firefox in Diagnose Firefox issues using Troubleshoot Mode to check if one of the extensions or if hardware acceleration is causing the problem (switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.
• https://support.mozilla.org/kb/Safe+Mode

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

the problem goes away when I start firefox in safe mode with all add-ons disabled. What should I try next? But to let you know....When I disabled all add-ons after a normal Firefox start up I get this error when starting firefox " exc in ev handl: typeError this.oroot.enable is not a function" I have to click ok to close the error window, but then when firefox window opens and I can go to web sites/link and the first error message that I reporedt is gone.

update also when I start firefox in safe mode with no options checked/selected firefox starts, and I can go to any web link/site without getting any errors.

ok, it appears that when I disable the McAfee Site Advisor 3.4.0 extension that all error messages go away. So it seems this is/was the issue. Does anyone know why and how to fix it?

If it does work in Safe-mode then disable all extensions and then try to find which is causing it by enabling one at a time until the problem reappears.

• Use "Disable all add-ons" on the Safe mode start window to disable all extensions.
• Close and restart Firefox after each change via "File > Exit" (Mac: "Firefox > Quit"; Linux: "File > Quit")

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

I got the same error message. Following advice from this forum, I disabled only McAfee Site Advisor and the problem goes away. That suggests either a direct problem with Site Advisor or a bad interaction with another plug-in. Maybe we should get on McAfee's case about this.

I have advised McAfee's product team of the problem and this thread, and they're looking into it now.

I only get error by clicking on a link provided by a Google search. No problem if I use another search engine.

I had a McAfee technician tell me I was just imagining this problem and that Java was the cause. Good luck with any help from McAfee. I disabled SiteAdvisor and all is well.

This is an issue only for SiteAdvisor users who are still on 3.4. This issue is fixed in the latest version of SiteAdvisor which is 3.4.1.195. Go to http://siteadvisor.com and click on download. This will fix your issue.

In the mean time, SiteAdvisor team will push down a JS update in the next 1-2 days to automatically fix this issue in 3.4.

Fantastic Davoud1. Turnaround time from McAfee is always very fast.Appreciate that

Thanks all. It seems we have a workaround right now and an offical fix is forthcoming. I believe this issue is solved for the time being anyway ;-)

Locking this thread since original poster has indicated it is solved. Please post a new thread if you need additional help.

-Michelle