Sounds like it could be 1 of 4 things:
- You've got an ip address conflict or some kind of misconfig on the network, if you've got a static ip set try setting it to DHCP or you're wireless settings are wrong, check the gateway address and subnet etc
- Driver conflict (Again unlikely) if you've tried the above try reinstalling the wireless card drivers
- You've got another piece of software handling the wireless and windows doesn't like it, for instance on mine i have 'Thinkvantage access connections' which promptly got removed.
- Bad wireless card, if none of the above work, try the wireless card in a different PC if you can.
Hope this is of a little bit of help :-)
