I am running Windows 7 64-bit Ultimate. For a little while now, I have been having the following happen with my wifi connectivty:
1) I turn on the computer and boot normally. The computer automatically connects to my primary home wifi network.
2) I attempt to change networks to another wifi network that I operate from home. My other devices have no problem connecting to this network.
3) After the attempt to change networks, the existing network disconnects, but no new connection is made. Eventually I am given the option to open as troubleshooter, which of course resolves nothing.
4) I can't open a list of available networks either from the taskbar or from the Network and Sharing Center.
Only rebooting restores my Internet access.
It was initially thought that this was due to a rootkit ZeroAccess malware, which may in fact have infected my computer, but the problem may be bigger. Here is the thread from the malware removal forum: