From another website
"Microsoft has blamed PC makers for an endless reboot issue that has afflicted some Windows XP users after installing Service Pack 3.
The company said that the problem is caused by OEMs loading an incorrect version of XP onto their machines.
"While the root cause of this issue is complex, it results from OEMs improperly placing a Windows XP image created for an Intel-based computer onto machines with non-Intel chipsets," Microsoft said in a statement. "Microsoft issued guidance to OEMs advising them to only load Windows XP images onto like hardware in 2004."
This four-year-old guidance initially accompanied the release of Service Pack 2, which Microsoft claims suffered the exact same issues where Intel processor driver tries to load onto non-Intel machines, sending them back into an endless reboot cycle.
While Microsoft is not specifically naming OEMs, ChannelWeb claims a technical advisor informed it: "I checked with the resources I have and it seems that we have not had any issues with any manufacturer other than HP."
Microsoft had not confirmed this report at the time of writing, and HP had yet to return a request for comment."