Perhaps I've found a reason?
I reformatted a couple of days ago, reinstalled XP and SP2 and many of my programs. Boot time reduced to a minute or so.
However, I found I couldn't hibernate the machine, it always went to standby instead. Then I found a M$ file which said that with over 1GB of RAM, hibernation was impossible - so I ran the recommended utility to counter this - and my boot time is now back to 5 minutes! Not the "reboot" after hibernation, but the cold boot.
Fairly typical, I would say: the OS has a bug which prevents something working, a patch is installed and this affects something else!
XP Home, 3.2GHz P4, 2.5GB RAM
Edited by Wol, 30 April 2007 - 04:42 PM.