Using Firefox 3.6.6, not a single webpage will open but every other version I've used works fine (currently had to revert to 3.5 to use access webpages).
My computer upgraded itself to Firefox 3.6.6 and when it did Firefox could access the web but would not open any webpages (I tried dozens). Firefox hums away for a second or two, then indicates that it is done, but displays a blank page. I uninstalled and reinstalled 3.6.6 several times with the same result. Finally I had to uninstall it and reinstall an older version (3.5)which works fine.
Every time Firefox opened
My computer auto-updated to v 3.6.6.
Mozilla/4.0 (compatible; MSIE 7.0; AOL 9.1; AOLBuild 4334.5009; Windows NT 5.1)