Remote Access & control of a Win2K Pro Workstation

Question? In an active directory domain I have been able to successfully remote into most Windows 2k pro workstations and control them remotely with a sweet tool call Gencontrol 1.1. However on some boxes I get ” error:5: Connecting to machine: Access is denied ” Which means I actually have to get up to find the machine to patch it or what ever. Why is this and is there a work around. I’ve goolged it but can’t seem to find a straight anwser on it.