can’t enable hibernation

hello
here’s my problem:
on a computer running win2Ksp4, I juste can’t enable hibernation.
that is, the hibernate mode tab is accessible, I can check the “enable” box, but when I click “apply”, I just get an error message saying that the file cannot be reserved, already open or in use by some other application…

I tried on another PC, because someone told me it could result of some interaction with scsi drivers or virtual drives… I uninstalled the a347scsi.sys driver and it worked…
but on the first PC, it didn’t.
I even removed my adaptec scsi controller and deleted the aic78xx driver, but it didn’t help…

anyone having a clue ?

thanks !