[wireless] DHCP doesn't work with WPA

Hi,
I spent some time trying to setup a WPA authentication between a D-Link 624
router and a laptop running Windows XP, with an built-in Intel 2200BG
wireless adapter.

The wireless worked fine without encryption. With WPA there was the message
"limited or no connectivity", though the signal was excellent. I couldn't
ping the router. As ipconfig reported an IP address of 0.0.0.0, I tried to
assign a fixed IP address to the laptop, and to my surprise the connection
worked with WPA.

Anybody has encountered that already?
Thanks.