iPhone 4s version 6.0.1 + AT&T data plan with tethering
Mac OSX version 10.7.5
Windows XP SP3 v 2002 + Intel Centrino Advanced-N 6200 AGN network adapter, driver version 22.214.171.124 6/2012
Problem: I can use my Mac (today) to wirelessly connect to my iPhone personal hotspot but my Windows computer doesn't see the hotspot in available networks.
Background: My personal hotspot would work for a while then drop out. I upgraded to iOS 6.0.1 Monday morning, and Monday evening a friend with Windows 7 could connect to my hotspot but I could not wirelessly connect the Mac to the hotspot. I went through all the troubleshooting: restored network settings, closed apps, restarted services, rebooted, verified AT&T still had me on a tethering plan - the only thing that fixed it was a complete restore, however my Windows XP computer still can't see it. It can see and connect to other networks. I upgraded the network adapter driver, rebooted, repaired the wireless network connection, released/renewed all ip addresses, and confirmed with Intel that the adapter supports WPA/WPA2. It can see and connect to other wireless networks.
This Apple Support KB article says I should be able to use the hotspot via wifi with "A device with Wi-Fi with support for WPA/WPA2 encryption," however the Apple tech support supervisor I spoke with today said the hotspot only works wirelessly with Windows 7 and Vista.