SYMPTOMS
When you try to restart your computer to complete the installation of Microsoft Windows XP Service Pack 2 (SP2) or Windows XP Tablet PC Edition 2005, your computer stops responding (hangs).

You experience this issue when you select any one of the following options when you restart the computer:• Normal
• Last Known Good Configuration
• Safe Mode
• Safe Mode with Command Prompt

CAUSE
This issue may occur if the following conditions are true:• Your computer uses an Intel Pentium 4 or Intel Celeron D processor that is based on Prescott C-0 processor stepping.
• Your computer has a BIOS version that is out of specification.

Note A BIOS version that is out of specification does not provide support for the processor that is installed on your computer.

More info here