Wireless cutting out (on computer end)

This hasn't been a HUGE problem, but now about once a day or once every two days my computer will stop detecting any wireless networks. I haven't seen a pattern in why it would do that and I know it's my computer because my roommates haven't had a problem. One second my connection's great and the second it's telling me, "You're not connected to any wireless networks."

I'm going to try and run another virus scan tonight, though I don't know if that's the problem. This computer is a few years old, but by no means ancient. I'd just rather not have the wireless card poop out if that's what's going.

Any advice?

what's your signal strength like?
does it still happen when the machine is right next to the wireless router?

Yep, it's right next to the router. I'm sure it's my computer because normally I can see six to eight other secured connections (and one unsecured), and when it cuts out, it doesn't detect any connections at all. I have to restart my computer and then it's fine.