Windows 7: Deleting old profiles

We would like to remove the profiles of users who login to windows 7 workstations.
Under xp a third party script worked but under windows 7 it fails to work.
The script is activated by an Active Directory Group policy (2003).
The problem seems to be with permissions surrounding user profiles.
Tried a scheduled task with "Run with highest privileges" ticked and ran as NT Authority\system but it does not work. If I login as an ordinary user the scheduled task should run as system and remove the old profiles. Even when logged in as administrator of the local box the script will not remove the profile directories.
It is called deleteprofile.vbs and was obtained from the www.
Am I failing to do something?