clients connected to a bridge shows same MAC bridge

Dear All,

I have a small wireless network having a AP and up to 10 cilent,
and at our client side wireless we have kept a ethernet switch and distributed to 10 to fifteen cleints through the cat5 wire.our all the locations are working fine.
but one of them wireless client and associated PCs(computers) are giving problem,problem is all the clients connected to this wireless shows same MAC address and that MAC address is of that wireless.I have reset/changed the wireless even same problem occures.
what could be the reason, please help me!!!

thanks
Ajmal