I myself don't believe there is a problem with the wireless adapter myself, I believe the problem is something awry with some file(s) in Win7.
Is the system at the Win7 SP1 level ?.
Have you run a full Anti-Virus and full Anti-Malware scan, maybe a scan for rootkits also?
For rootkit detection, I use Kaspersky TDSSKiller
http://usa.kaspersky.com/downloads/tdsskiller
If anything really bad is found, I would turn off System Restore to flush out old restore points,reboot, then turn on System Restore and create a new restore point.
To really verify if there is a problem with something in the Win7 software, if you have one, you could use one of those wireless USB adapters (disable your current wireless adapter in Device Manager temporarily), install the USB adapter drivers and see if you can connect. If you get the same symptoms, something is wrong in the OS, in which case I would try to do a system restore to a date before this problem started.