DWL-900AP+ and MAC munching

[Akash]

Hello,

I am having very weird problems when I plug my DWL-900AP+ into a hub or
switch.  Somehow, sometimes pings even to local machines time out.  We
have a DSL cable modem that seems to function fine but just stops
working whenever an AP is plugged in (in client mode) at any point in
the network.
Did anyone else have the same problem?  I have a feeling it is due to
the way the AP deals with MAC addresses, and maybe inadvertently it
'steals' the paths and reroutes it to the AP which is at a remote
location.  
Would a solution be to enable MAC filtering and only enable the machines
that are really going to use it, as well as our internet gateway
machine?

Any help would be great!

Akash Heimlich