Of the 6th PC? If this is a classroom setting or a lab of some sort, talk to the room's manager or to the teacher or your boss - or whoever told you to go to that room to do whatever it was you were supposed to do. Sounds to me like the 6th PC isn't set up like the other 5, and we will have NO way to diagnose this problem remotely.
We like to offer help, but sometimes the question makes it clear that hands-on is very likely to be required. This appears to be one such case.