I've tested the drivers 77.72, 81.98, 82.16 and 82.69 with FX5900XT and 6600GT both AGP. I can confirm that the shutdown works with the driver 77.72. If I use the newer drivers the shutdown works fine with the FX5900XT, but not with the 6600GT. I think the problem is concerned to Geforce 6 and higher - not to the FX series. Next I test a 7600 PCI-E. One possible solution: I've installed the PLoP Boot Manager 5.0.3 in DOS Mode. After reboot I choose shutdown in the PLoP Menu. It takes about 14 seconds more to shutdown.