create an automated task:
Make a small batch file with a single line:
Put it in a folder somewhere
Open the task scheduler and create a new task. Make sure that you check "Run with highest privileges."
Trigger should be set to "On workstation unlock of any user".
Action is "Start a program". Point it you your batch file.
Under the Conditions tab, make sure "Start the task only if the computer is on AC power" and "Stop if the computer switches to battery power" are both unchecked.