Connection Keeps Dropping

Hi, I'm wondering if anyone else has had this problem with a DI-514.
Basically up until yesterday, my wireless network was working fine.
Yesterday, I had to disconnect and unplug the router while I was moving
some stuff around. When I plugged everything back in, I couldn't
connect to my wireless router (D-Link DI-514) anymore! I am able to
get it to work whenever I power-cycle the router. But after about five
minutes, I lose the signal again (and the WLAN light goes out too).
I've tried re-updating the router firmware and my wireless card drivers
(even though I already did that and had it working). I tried
re-setting my router to factory defaults. I tried taking the router to
a friend's house with a cable modem - same problem. I also tried
changing channels on the router, I tried Channel 6 and 11 with no luck.

Brief specs: Windows XP Pro. My connection is a T1 (dorm room - but
the router works fine while hard-wired to my ethernet card, and I can
connect to other wireless networks nearby). I have no problem
accessing the Internet when connect my ethernet card (same computer) to
a port on the router - I just can't access my router wirelessly here or
at home. I'm thinking it must be some signal problem where the router
stops broadcasting after a few minutes, but I can't figure out why this
is happening all of the sudden when it was working a couple of days
ago. I also know it's not my wireless card since I can connect to
wi-fi networks on campus, just not my own.

Any help is greatly appreciated.