OK... Here is what I have
2 Computers, 2 simple problems, 2 mind boggloing cases.

Here is the First:
OS: 2K
This is a computer that in part of a lab. It is hooked up to the network through a large hub in the room. All is well. Well, we are supposed to have the students log in and work on the computers. This one refuses to get on the network. I have checked the domain, checked the wires, checked everything else that I can think of. It Still will not log in. So, I change out the Computer and put another in it's place. It won't log in either and that one was loggin in just fine. Now the one that was there before works in my office.

Problem 2:
OS: XP Pro

Teacher's computer; a must fix now kinda thing. Out in the room, it says it has no connection. I hook up a 'loaner' computer to the same jack and it works!
I hook up the origional computer, and it works in my office!

Any ideas on either one?

Possible solutions:

Computer 1:

First pull the power out of the hub and plug it back in just in case.

This is most likely one of two things:

1. Bad cable going from the hub to the computer: Try a known good cable
2. Bad port on the hub: Try a known good port

Computer 2:

I'd have to know more about the equipment in use: What kind of hub (model) and what kind of computer. The steps I mentioned above should be taken for this computer just to make sure. If you Right Click "My Network Places" and go to "Properties" you will see a connection called "Local Area Connection" or something like that...Right click it and select "Properties", by "Configure" it should tell you what kind of network card you are using, write that down and post it here. Click "Configure" go to the driver tab and write down the driver version and post it in here for us.