wireless keeps disconnecting - please please help!

Hi, I have a small setup at home, I have a PC, that has a Belkin PCI wireless card - this connects to a Belkin wireless router.

I also have a Laptop that has a wireless connection, and a PS3 that connects to the net via wireless.

Up until last week everything was working okay and then I changed ISPs... We have a lovely connection to the router, and the PS3 and laptop all work just fine but the PC keeps losing a connection every 5 mins or so - I have tried to google for a solution but to no avail - I just can't work out what is wrong???

I have fiddled with settings while trying to set up my ISP as I got a bit muddled but I thought I'd put everything back to how it was - I haven't touched the hardware.

Can anyone point me in the right direction that i can try and sort this out as its really doing my head in!!

many thanks!

crazy ma

Is it possible you have a cordless phone that may have switched channels?
Possible RFI?

Are you running WPA?

Could be a lot of reasons, need to narrow it down.