如果CPU是Prescott C0 Stepping 的話(請用CPU-Z之類的tool查看)
請等新的BIOS吧
或是試試下面的方法

Windows XP won't boot after installing SP2 ?a BIOS update may be necessary

Solution 2
If you have already installed XP SP2 and have a PC that will not boot because of this microcode version problem, there are two workarounds you can try to get to a bootable state.

In the BIOS setup you should temporarily disable the L1 and L2 cache. On some motherboards, this will allow the computer to boot. You should then remove SP2, turn the L1 and L2 cache back on, and then update the BIOS to reflect the correct microcode version. After completing these steps, you should be able to re-install SP2 without running into this particular problem again.

If disabling L1 and L2 cache does not work, you can use a second workaround suggested by a representative at Intel: Boot the problem computer with an alternative OS or to the safe mode command line if possible. Assuming you can get to the Windows directory on the boot partition, navigate to this file and change its name so that it does not load the next time the machine is booted:

windows\system32\drivers\update.sys
After rebooting you should be able to install XP SP2, but keep in mind this is a temporary fix鍟he system will be unstable until you update the BIOS and reactivate the update.sys file.