If user already logged next user can't logon to wireless network

Hi - I have a laptop (Dell 630m XP Home) and desktop (Dimnension XP
Pro) on a netgrear wireless network.

I notice that if I log on to the laptop and someone else is already
logged on the newly logged on user will never be able to get onto the
wireless network.

If I go to task manager and log off the other user it all connects up
ok!

This seems to be the same on the dimension desktop and also the same
thing happened with previous (Lynksys) router.

Any ideas?

Thanks

Andrew