Forum Moderators: phranque
It sounds like a permissions problem - it may be that IE is transparently presenting your account credentials so you only get the prompt in non-IE browsers.
You need to check the filesystem security permissions on the wwwroot folder (IUSR_*yourcomputername* is the user account IIS uses to access the filesystem) and check in the IIS mmc "Internet Information Services" under Properties -> Directory Security that "Anonymous Access" is checked.
HTH.