I had this problem; something about a network problem; tried to repair windows and it didn't work. Tried to re-install windows XP and then IRQL_NOT_LESS_OR_EQUAL kept popping up.
I came here to check for solutions and checked several other places.
Anyway, my solution was to pull all the cards and connections that were not necessary to try to narrow it down by trying to re-install each time.
It was my network card.
Hope this helps!