This time I went into Device Manager, found the WLAN adapter, right clicked on Uninstall and pressed the OK button without choosing to delete driver software.
After a reboot, Vista automatically installed the adapter again, and the WLAN led was again showing signs of life!
Fn+F5 now shows the option to turn on and off the WLAN adapter.
I lost control of the WLAN adapter because I disabled the WLAN adapter while being connected to a wired network. Very strange bug, but this has now happened twice.



