Guru- like me you have probably been digging around for info. Maybe something here will help:
http://aumha.org/win5/a/shtdwnxp.php
They mention Roxio Easy CD Creator (which I have and did not have a problem before when it was installed and I have not even installed since the last XP reinstall) so that is not my issue. I have not gone into BIOS to double check my settings there. I did send of a question to Antec support but it sounds like there may be something besides the buttton going on. Should my computer be set for "hibernating" or not- it is not right now.
I think it is some sort of power management issue.
I was able to transfer all my photographs from my other hard drive (thank goodness!). My "Favorites" had somehow vanished from that one but I have another old drive with an older version I was able to hook up as a slave and copy over. Saved having to search for all those websites again!
Just Windows XP and its updates (and a few drivers I needed to be able to get the updates- I think that includes up to Media Player 11 and .net3.5)took up 10gb on my hard drive. I just checked the box and it says minimum requirements 1.5gb space.