Wireless Issues

So a coworker of mine has had some really funky issues with his wireless stuff on his laptop. Here are the facts (in no particular order):

• the wireless works fine when he's at home
• the wireless sometimes works with the on-campus network or the network in the office
• when the wireless isn't working, the network he's planning on using usually shows up for a few seconds on the available list, then disappears
• occasionally the wireless will work for an hour or two, then suddenly cut out
• other networks appear on the list, but they cannot necessarily be connected to
• this was originally with the internal wireless card - he just bought an external wireless card, and it does the same thing
• he's tried reseating the card
• he's tried reimaging his computer. twice.

I assume it's something with the motherboard, but he's hoping not and can't find any information himself, hence my bringing the issue here. Any ideas?

Jam it back in, in the dark.