Symptoms: the Windows XP WLAN connection icon always shows “connecting”, and the router’s event log will show many events about “authorization failed”. Probably, using a WLAN connection without encryption is still possible (according to a forum report), but that has not been tested. Also, the “list available WLANs” function does not work on any call to it.
The reason is simply the installation of the Service Pack 3 for Windows XP, in a version as recent as 2010-08-09.
Many people report such a kind of problem with a wide diversity of WLAN hardware after installing Windows XP in an “unclean” way. That is, without closing all programs first. However, in this case the SP3 installation was tried twice, once from Windows Update without closing tray applications, and once by downloading the self-extracting CAB archive and installing it in Windows protected mode as recommended. However, the error was the same in both cases (and was even worse in the latter case, as the card could not even list any WLAN). So it is best to simply ignore the SP3 update in this case.
To uninstall Windows XP SP3, simply use the Windows System Recovery tool.