This has to be one of the strangest problems I've encountered on Windows. So here's the situation: Windows 7 64-bit and a Asus WL-138G V2 that doesn't want to be enabled. Normally, you'd just double click to enable the adapter and be on your way. No dice.
What's the problem? Kaspersky Internet Security 2010. Uninstall the thing, reboot, and the WLAN device goes back to normal. It's amazing just how screwed up things can be in Windows. It's pretty obvious that a network device is meant to be used for connecting to the network.
Whatever possessed Kaspersky to keep the thing disabled? It's not even set to block network traffic. I have no idea. I just know this happens to every single security software out there. Every once in a while, I'll come across some network related issue that shouldn't exist. And in the end, it usually turns out it's the innocent looking antivirus software that's the culprit.