WiFi Bridge works except for windows

I have a small LAN with a windows domain. Very vanilla setup with a
Router, switch, 802.11G AP, a server/DC and some workstations &
wireless laptop. Now I want to add a workstation using a wireless
bridge instead of either wired Ethernet or WiFi card.

The workstation works perfectly when connected via Ethernet wire. When
I replace the wire with the configured wireless bridge I can use the
Internet connection and can ping the server and all other machines,
but I can't see the other machines or shares in windows. (Windows
Explorer hangs for a long time then times out). Laptops using WiFi
cards & even a squeezebox work perfectly. Any ideas where I should be
looking to troubleshoot this?

It almost smells like a windows or compatibility or WiFi security
issue, but right now even those make little sense to me. Tried 2
different bridges (Squeezebox2 & D-Link DWL-G730AP Pocket router). The
Squeezebox can't even log into the domain. The D-link could. Neither
can access shares or computers in windows explorer. Funny thing is I
think they are BOTH using the DC's DNS server (both for internet & the
D-Link also for logon to the domain ). Same behavior when disabling
all wifi & router security. Where should I start? Are there known
incompatibalities or good (but inexpensive) devices I should be aware
of?

TIA