Unable to access router wirelessly

I have a unusual problem.

I have a macbook pro with dual boot. (MacOS 10.5.2 & Vista 64bits).

I can access my router from Vista using the wireless built-in card,
but no luck with MacOS.

And before everything was prefect on both sides.

I tried resetting my router to factory defaults with no luck.

I brought my Macbook to the store and they tried to connect on their
hot-spot without any problem!!

I went back at home, formatted the MAC partition, installed MacOS
10.5.1 and I got connected. Then I upgraded to 10.5.2 and lost
connection again.

Why is 10.5.2 doesn't connect at home on my D-Link Dir-625 (only on my
MAC partition) but connects flawlessly everywhere else??

Thanks for your help.

Marc