I had this same problem with my Dad's computer. Spent many a night trying to figure it out. Even went so far as to get him a new motherboard thinking that would solve the problem. Obviously it didn't. It wasn't until I was trying to shut the computer down and it would just hang there that I put my hand on my head and lookeed down in thought. That's when I noticed the light on his HP CD Writer was constantly on. I disabled it in the Device Manager and the shutdown problem was fixed! I was SO HAPPY that I stayed up until 3am switching back the cheapo motherboard I had borrowed from work to put his old one back in. Everything worked and I was the happiest guy in the world!!!
Needless to say, the CD-ROM might not be your problem, but it's obviously some piece of hardware that is holdig up your system. I suggest disconnecting everything from your computer that isn't necessary. Like CD/DVD drives, Zip Drives, etc.... I also suggest taking out all your PCI cards (sound card, network card, modem, etc...). Also take out any AGP cards if you are able to hook your monitor up to onboard video. Then turn on your computer and try to shut it down and see if the problem still persists. If it does turn on and shut down correctly, then it's just a matter of trial & error with each piece of hardware. Reattach one piece of hardware and try to turn on and shut down your computer. If that works, move on to the next one. Keep doing this until you find what is causing the problem.
Edited by Fenor, 07 December 2005 - 09:13 PM.