to check if hang-the-9 is correct * i think he's on the right track * have another employee attempt to log on using that PC. She can log on anywhere else but can anyone else log on from her terminal? If no one else can log on from that terminal we know that hang-the-9 had a break and run *pool terminology for he was right :P*
I'm not quite sure what server os you're using, but there are several settings in several server OS's that can limit certain computer's access, not just group and user. Start with the local terminal and then back to the server.
Hope this helps.