When vista computer comes online, it kicks off all other computers

I have a wireless network with 3 computers as follows:
OSX
XP and
VISTA

I have never had any problems with the OSX and XP computers where it was
just two of those. Since the Vista computer has come into the picture I have
been having some problems. Let me describe them briefly....the two non-Vista
machines are online and working just fine...then as the vista computer boots
up, the user logs in and the wireless card in there tries to connect to the
network, the other two laptops get kicked off for about 30seconds....Has
anyone else run into this issue? Any one know how to fix it?

Thanks.