OK. I installed windows XP Pro and still have the problem. I reformatted the HDD when I installed it and did all the windows updates. So now I believe that there is something going on with the usb ports that is causing the problems. When the system is up and running it seems to work fine, but as soon as I install a usb device, the system hangs. Also, if I turn off the computer and install a usb device, the system will not boot, in safe or normal mode. The system is under warranty from Best Buy (the computer has been there 4 times and they tell me everything is fine), so it is going back -again. Do you have any experiences with Best Buy or the geek squad? They don't seem very thorough in their work (to me). One of the reps told me that the power issue was something that I would just have to deal with, basically just hold the power button until it turns off. That's sort of like buying a manual transmission car and having the service rep tell you that they don't know why the ignition doesn't work, but the good news is that you can push start it???