I have two identical laptops, both Lenovo T61p's sitting side by side.Machine Ais loaded with Vista x64 Enterprise, machine B with Vista x64 Ultimate. Same wireless card (Intel 4965AGN), and same wireless driver version in both. Current patches on both. Both machines were working with my access point just fine for over 1 month until today. I unplugged the access point from AC power, then plugged it in again after a few hours. The access point showed up in the available networks list in machine A, but not in B. Other wireless networks in the vicinity show up in both machines. I am running WPA2-Personal with AES on the wireless network with MAC filtering. I disabled security and MAC filtering on the access point completely, but I still can't see the access point on machine B (A sees it fine). Rebooting machine B several times has not helped,nor has changing the channel selection from automatic to 13. This is not the first time I have shut off and restarted the access point, and both machines always recovered before. Nothing has changed on machine B in the last month. What can possibly be wrong with machine B that it can't see the access point? If the laptop network card went bad, I wouldn't be able to see any wireless networks. If it was a driver issue, both machines would be affected. If it was a problem with the access point, orinterference, both machines would be affected. If it was wireless security-related, shutting off the access point security should have made the issue go away. And why did it happen now, when I've powered off the access point before? Is this some leap year bug that affects Vista Ultimate but not Enterprise - that seems pretty unlikely, too. Help, help, help!

Well, just in case anyone has the same problem and runs across this posting in a search... Wireless channels go from 1 to 13.The access point was set to choose a channel automatically .On Vista Enterprise, I can choose from 1 to 13 as well. Under Vista Ultimate, I can only choose 1 to 11 and it was set to 11. Apparently the access point was auto-choosing a port of 11 or under until I reset it the last time - after that, it stuck to 13. I changed the access point to always choose channel 11 and all was well. Considering that I have the same hardware and same driver under both Vista Enterprise and Vista Ultimate, I find it weird (to say the least) that I am limited to 11 channels on Vista Ultimate.