You didn't share the error messages. I know a certain compromise security message but can't recall it. You have the clues that need to be shared.
In closing, put the "error message" in quotes for clarity. Also, who's the IT staff here and what training and books do they use?
Okay, I have several machines running Windows XP and Windows 2000. Some have roaming profiles and others do not. First off the roaming profiles take forever to load, but that's another topic. The problem is that one of my users can log in, but has little access. As soon as I put her log in info in, I get a message saying that it can not find her profile on server. If I scroll down, I also get a detail message saying there was a compromise in security or something to that effect. So if you press OK and let it load to the desktop, it's using a local cache profile and I can not map any drives.
On a second computer, the user can log in and it will pull the network profile, but if I go to map a drive (browse by IP) I get presented with a log in box. If I try using the username and password that I logged in with, I get an error saying it's already tried that.