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 > 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

I tried the Safe Mode - still have the same problem, Google Maps goes into a permanent LOADING mode. Google Maps works fine in Internet Explorer and Chrome and worked fine in FF 3.x before I upgraded to FF4.

Problem solved - I think. I normally block most cookies, including all from Google. Apparently, Google has changed something and now I need to allow session cookies for Google Maps. At this time, I don't think this is a Firefox problem at all.