Problem with network at college...

Roommate has a adell Inspiron 8500 with built in 10/100 nic. Last night he could go online, surf, talk fine.
Today Zip.
Checked NN, cable, and anything i could think of, but nothing seems to work!

He cant see other users, workgroups or anything. Connected him to my cable, did the same thing, but works for me.
Any ideas?

did he disable any services recently? I know I followed a guide the other day that said it was ok to disable net logon, but you need that service, plus the workstation service, to be able to login to networks automatically. with out those services he wont be able to see any workgroup computers

Does he have an IP? Can he ping other computers on the network by IP? Check cables, and link lights?

What changed between last night and today?