If not powered down backup works..why?

Archived from groups: microsoft.public.windowsxp.help_and_support (More info?)

My Ghost 9 backup software wont do incrementals. No matter what I try it
will only do a baseline backup. If I leave the PC on overnight however, it
WILL do a
incremental (in other words PC not turned off between backups).
I have updated, reloaded, rescheduled, tried different schedules etc. I
also do not do defrag or schedule a defrag (which I read in a FAQ on will
cause this).

Does the fact that if I dont power off between backups provide a clues as to
what I can do to correct this? Does windows somehow scamble the disk so it
looks likes its defragged when I power it up again?

thanks