USR router goes down frequently, when AP is in use

When I'm using my laptop's wireless interface, it connects to a NetGear
MA102 access point, which in turn is connected to a simple MAC level
bridging device, which in turn connects to a USR8000 DSL router with
wireless interface.

Lovely as it is when this works, it will do this only for a while.

About once per hour, the router will disappear for a couple of minutes.
During that time, it may not respond to pings; sometimes it does, but DNS
doesn't work; whenever DNS doesn't work, routing doesn't work either.

While the laptop has a network cable plugged in, i.e. the access point is
not in use, that doesn't seem to happen at all.

A friend told me about problems with "broken" network packets (runt ??), and
NAT tables flowing over; he's had this with his gear (different brands), and
finally received a workaround for his router.

When I called USR support today, they weren't very helpful. The person told
me that he's not able to help me with ... pretty much anything ... not even
help with configuring the logging function on the router ina way that might
help me nail down the problem.

I would very much appreciate any hints towards finding the root cause, a
workaround, or even a solution !!!