Did you install SP3? If you did I have had a problem that fdoes as you describe and the Bios had to be upgraded to a newer version. Try updating the Bios, make certain you have a good broadband connection as any errors and *********** board is toast!, if you have SP3 already installed.
Let me know how you get on please.

I would like to refer you to the following article for a detailed diagnosis of your problem:
http://www.fixya.com/support/r6556655-troubleshooting_laptop_wifi_connectivity

If you are sure all drivers are correctly installed, try the tips in this article, & hopefully they might be helpful.

Sorry, but i saw this searching something. I had same problem one time ago. Locate the wireless driver and install it, it is a gigabyte card. and also install the external keys driver, and it will come to life again!!!. If you has not this case anymore, forget it.