ok i have just set up my home network

I got a belkin wireless router plugged into my modem (NTL Cable)

WiFi enables phone

2 Laptops

2 PCs

All work fine except one PC. It finds the network, has 90% signal strength, then goes on/off/on/off every 30 seconds or so and sometimes the only way to pick the network up is by disabling the card and then enableing it again. sometimes it picks the network up but will not obtain an IP address, sometimes it works fine for a few minutes

all settings look ok, set up the same as everything else, that works fine

really bugginh me. also the PC had the same problem in my girlfriends home wifi network

any ideas? card fecked? its belkin also