Billion Bipac Ac 643 problem

Hello everybody,

A friend of mine is having problems with his Bipac AC 643 Wireless
router/firewall. The two desktop machines he has work fine with it with usb
receivers, but his laptop with a build in WNC 802.11b usb 300 connector will
not build a decent connection for at least 10-15 minutes after booting
(Windows XP.) It all used to work fine for a couple of weeks when he'd
bought it and then all the sudden the problem started. When it connects it
goes like the clappers, but he shouldn't dare to reboot...

Anybody know these problems and even better have a solution?

Thanks a lot in advance!

Mike