Firefox 3.6 ask mi to download ???
Clear the cache and the cookies from websites that cause problems.
"Clear the Cache":
"Remove Cookies" from sites causing problems:
You can also check for problems caused by extensions.
Do a malware check with some malware scanning programs on the Windows computer.
Please scan with all programs because each program detects different malware.
Make sure that you update each program to get the latest version of their databases before doing a scan.
You can also do a check for a rootkit infection with TDSSKiller.
the google product forums are full about this issue: http://productforums.google.com/d/topic/google-plus-discuss/QvaQaWgYuQE/discussion
there's not much you can do on your end - hopefully google will fix the problem soon...