Linksys AP, Linksys pci card issues

We have a linksys wrt54g router in place using WPA. three machines connect to it using some belkin cards and they work fine. I installed 6 new linksys wmp54g pci cards in 6 new pc's. they get a connection but drops it every 10 secs or so. the other clients were being dropped too. however if i disabled wpa everything worked fine. beside updating the firware on the router (up to date already) and the drivers for the nics. what could be causing this. Can WPA really do this to the wireless connection? Also the PC's that were dropping wehn wpa was enabled would crash. windows would freeze up thet start to work, then freeze up again. These are all new Dell PC's.
thank you for any suggestions.

-Ed

 

Wireless

I have had a similar issue but have not solved it