Re:
Hello,
Is is a common issue in fresh installations of Windows XP. It happens when Windows doesn't detect that your PC is ACPI compatible, or
Advanced Configuration and Power Interface compliant, or if the BIOS power management settings is not set correctly. It can also occur if your PC is not ACPI compliant, but if in the past your PC had standby and powered off automatically, then your PC is ACPI complaint.
First, go into your BIOS and check to see if there is an option allowing you to
Enable Advanced Power Management or something along those lines. If you can find this settings, or if you can't, then move onto the next step.
Check to see if your computer is ACPI compliant by going into
Control Panel > System > Hardware Tab > Device Manager. Once the Device Manager window appears, click on
Computer label and the tree should expand.
There's a few more steps you'll need to follow if your PC is ACPI compliant. There is also a solution for this issue if your PC is not ACPI complaint.
I've found this Microsoft Support Webpage from their knowledge base which will tell you what to do from there:
Article ID: 810903
Problem: "It is Now Safe to Turn Off Your Computer" error message when you try to shut down your computer.
http://support.microsoft.com/?kbid=810903
This solution should also resolve the Standby problem.