Lets see if this helps:
Boot youre pc in safemode (hit f8 when booting up)
Click Start>Run and type in: services.msc
Click OK
In the Services window find:
Power Manager
Select/highlight and right click the entry, and choose: Properties
On the General tab, under Service Status click the Stop button
Beside: Startup Type, in the drop menu, select: Disabled
Click Apply, then OK
Open
HJT and click config > misc tools > ?delete an NT service?
Copy and past:
Power Manager
Click OK.
Then fix this entry with hijackthis:
(if still pesent)
O23 - Service: Power Manager (PowerManager) - Unknown owner - C:\WINDOWS\svchost.exe (file missing)
Reboot when done and see if the problem is gone.