Are you using the Google search bar on the Navigation Toolbar ?

Works for me.

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

• Don't make any changes on the Safe mode start window.

See:

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

• Google search is from the line that contains the URL address.
• It seems to fail every time for me.

New information: It is not just a Google search. 1. New tab 2. www.nvidea.com 3. Select a link and click. 4. Going back to www.nvidea.com does not work. I am guessing any first link on a new tab will fail to get back to the starting page.

Did you check if any of your extensions is causing it?

In "Safe Mode" the problem appears to be gone.

All Active Extensions:

• Firefox Sync 1.7
• Java Console 6.0.24
• McAfee Site Advisor 3.3.1

I would think that these are very common extensions.

'HP Smart Web Printing 4.60' is "disabled" as incompatible with Firefox 4.0.

Update: Disabling McAfee Site Advisor 3.3.1 fixed the problem. The last update to McAfee Site Advisor was April 06, 2011. Can't get more current than that.

I had the same problem and disabling Mcafee SiteAdvisor worked for me too. Thanks for posting, this had been bugging me for a while now. Hope McAfee fixes it eventually. At least Web of Trust still works.