Just worked on a laptop with the same problem recently. What I finally did to fix it was create a new Wireless Profile. I can't tell you how to do it now as I don't have a Windows 7 laptop available to model it on, but once I did that, I could see the available wireless network connections again and was able to connect with no problem.
It's been working well for a week now.
Okay, open Help and Support and enter network profile. That will get you there.