This is a bit of an odd one.
Every time my roommate puts his computer to sleep (an HP laptop with Windows 7), the WiFi goes out for a minute or two. It used to happen with my desktop, too, an older Dell with a WiFi card, but it doesn't seem to trigger it any more.
The router is a Trendnet TEW-639GR with up-to-date firmware.
Any ideas what could be causing this?