Update: I found out the exact source of the problem and it is Windows and how it is detecting my dual-core processor. I decided to do some more testing this weekend so I reinstalled the illegitimate copy of windows xp today, but shutdown didn't work at first. I powered back on and checked Control Panel>Power Options and went to the APM Tab and enabled. After doing that, the pc shutdown properly. The reason why shutdown seems to work with the illegitimate cd activation code also seems to be because it detects the computer in Device Manager as a "standard PC" instead of an "ACPI Multiprocessor PC." Seems the illegitimate and legitimate CD keys default to some sort of preset configuration...I did not know this was possible.
I then decided to install the genuine edition again. After installing it on the same illegitimate cd, but with a genuine activation code, the APM Tab in Power options is no longer present and the PC now detects as an ACPI Multiprocessor PC in Device Manager. I have no idea why it is, but now proper shutdown is impossible once again.
After that, I found a Microsoft hotfix which looked like the answer to my problem. It can be viewed
here.
I installed the AMD dual core optimizer driver/software before applying the hotfix following a restart. After installing the hotfix and restarting, the PC booted up but then asked me for a login password for my account. The problem is, I didn't set up a password to begin with and I had to repair my installation.
The repair finished and this time, I set up a password for my account before trying the hotfix again. No go...had to repair again because I couldn't log in with the pw I set up. Gah!! The frustration I felt.
I am writing this from the PC giving me issues and since this hot fix doesn't work, I'm not sure if there's anything else I can try aside from what Bchivers suggested in the last post. I respectfully don't believe the single click shutdown suggestion will alleviate my issue, however.
The TSSHUTDN function from the command prompt suggested at aumha.org did not work.
EDIT: All of the aumha.org suggestions have failed me now...although I have not tried the ?ShutNTdown" registry solution yet.
More suggestions would be appreciated!