Xbox Extender "Network Issue"

I've got my Vista Ultimate PC hooked up to my Xbox "extender" via 100MB
Ethernet. This setup works fine, but I keep getting a "Network Issue" box
in the upper right corner of the screen when viewing content on my TV via
the Xbox extender. Other than the message appearing I don't notice any
distortion or jumpy content. I've stepped through the "Network Tuning"
offered by Vista, but in all cases the measured bandwidth is WAY above the
required minimums.

So, how do I get rid of this message?

TIA,
Bill