Immediate reboot after hibernation

Dear all,

in order to save energy, I would like to be able to remotely

shutdown / wake on LAN my up-to-date-patched XP Prof SP2 (Dell

Optiplex 745) machine.

I created a small shortcut to %windir%\system32\rundll32.exe

powrprof.dll,SetSuspendState Hibernate to be able to hibernate via

remote desktop, and successfully use AquilaTech's WakeOnLan to reboot.

However, since sometime/some patch (cannot reproduce what exactly

changed) a hibernation leads to an immediate reboot after a random

amount of time (usually several minutes). I am sittinng behind several

layers of firewalls in a big network (university), so wake-up-signals

from "out-in-the-wild" should not be the issue (and that should not be

possible without the MAC should it?).

I have searched the net for some time now but could not really find a

solution

Has anyone a hint for me?

Thanks in advance

Tyler