network fades on T43 Ubuntu

[stevext]

I have Ubuntu Breezy on a T43, dual booting with XP, and have a network connection problem that seems strange to me. When I boot into linux the netwrok connection works fine, then fades and drops out after a while. Sometimes I can ping the router but not reach anything out on the web. Sometimes - and this is what seemed really odd to me - I can ping, say www.google.com, though with some packet loss, but when I try to ping the router it says host is unreachable. Eventually the connection drops completely and I can't reach anything. Ocassionally, however, the network connection comes back for a while.

The other computers connected to the router meanwhile connect fine, and when I boot my T43 into XP the network connection works reliably.

I connect with an ethernet cable to the router.

I will appreciate it if anyone can suggest even where I start to try to figure this out.

Steve