Cannot detect wireless networks

I am running Windows 7, SVP1 and over about 5 days slowly lost my wireless connection. (example: clicking a link would disable the network, but it would reconnect in a matter of seconds.) Finally there was no connection.

In Device Manager the wireless card reported that it was working correctly. I downloaded and installed the most recent driver.

If I go to Control Panel\Network and Internet\Manage Wireless Networks and try to Add a network then I get a dialog that says "An error has occurred".

I purchased a new USB Wireless Adapter and although the installation completed successfully, its behavior is exactly the same as the internal card. Device Manager says it is working correctly but I cannot detect the network or add a new one. (BTW, the network is working just fine with other computers, printers and iphone.) I am currently connected with a wired LAN connection.

So I am stumped. If any one has a suggestion as to what to try next I would appreciate hearing from you. Incidentally, the network has worked just fine for the 15 months I have had this computer.

Many thanks,

Nitram