We am using Yahoo messenger 8 in our office. We are in 2003 domain and xp - sp2 clients. In some systems we are facing a different problem. In admin account messenger working fine. But in normal user accounts its giving the problem. Its not logging into the messenger.
What happens when the users try to login? Any errors?
Do you know if group policy on the domain may be preventing the execution of the Yahoo Messenger .exe (yim.exe, I think)? At work, Firefox.exe is blocked by GPO for most users, except members of IT....I'm wondering if this is the same case at your place.