|Difficult to say. |
It may be that power settings in windows has changed or that a bios entry has changed how xp was installed and what "states" are available. I have found that in more cases than not, some program is messing up your sleep.
I generally return to OEM by following the owners manual and that sort of feature works again. i wouldn't do that just for this issue.
You may be able to press the shift key when trying to power off. It may offer that choice.
Look at power management in control panel.
1/3 of highway deaths are caused by drunks. The rest are by people who can't drive any better than a drunk.