megamorf, thanks for your input. I have looked at the BIOS setup and all the wake-up options are disabled.
My windows XP machine will go through the hibernate process, but then immediately resumes. I've tried all the recommendations I've seen such as unchecking "allow this device to wake the computer". It used to hibernate perfectly, but since something changed it has the behavior described. Also, XP doesn't have the logging capability that would identify what is bringing it out of hibernation. Any suggestions would be appreciated.
Jasper, thanks for your response, the changes were many and complicated. My system had been deteriorating functionally and I did a number of in-place system restores, reapplying MS updates and fixes to try and get it back to normal. I had MCE 2005 installed and at this point it shows MCE 2002 with SP3. The roll-up to MCE 2005 apparently didn't happen or didn't complete. Since I don't use MCE features I don't care, and my system works well except for this hibernation problem.