I had this problem a year of so ago, so I went back and re-read that thread(s) to try again. Alas, I did the suggested fixes but I still get a maddeningly slow shutdown. I can click "Shutdown" from the 'Start' menu and the computer does nothing.
I can hit Ctrl > Alt > Del (the 3 finger salute

) and use the 'shutdown' option and 'turn off" from 'Task Manager' to get the machine to shut down, albeit very slowly. But this has worked so far to shut down quicker than before just hitting shutdown from the 'Start" button. .
Hitting 'Start' > 'Turn Off Computer' is either horridly slow or doesn't work, so I use the method I show above (using the Task Manager options). If I happen to run something that requires a restart to take effect, the computer goes to the 'Windows Is Shutting Down' screen
immediately but then hangs. So I manually hit the power button and restart manually.
If I want to turn the machine off because I'm finished, I use Task Manager and just leave it alone and it will turn off. Just takes a while. Here is the
TSG Sysinfo file requested that I supply. I also got the current "Hi-Jack This" version and ran and saved a log file if needed.
NOTE: In info below 'C' is main HDD, 'F' is an extra HDD I have installed and 'G' is an external HDD I use for storage, backups, etc.
Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows XP Home Edition, Service Pack 3, 32 bit
Processor: Intel(R) Pentium(R) 4 CPU 3.00GHz, x86 Family 15 Model 3 Stepping 4
Processor Count: 2
RAM: 1533 Mb
Graphics Card: Intel(R) 82865G Graphics Controller, 96 Mb
Hard Drives: C: Total - 53074 MB, Free - 24402 MB; F: Total - 38122 MB, Free - 37813 MB; G: Total - 200294 MB, Free - 105320 MB;
Motherboard: Dell Computer Corp., 0F4491
Antivirus: avast! Antivirus, Updated: Yes, On-Demand Scanner: Enabled
As always, thank you for your time and help.