ad logon scripts execute permissions

Testing Environmet: Ms Virtual Server 2k5 R2 Testing Environment Host OS: Enterprise Server 2k3 x64 Edition Testing Environment Hardware: Intel P4-D 940 i975X Chipset 4GB RAM Testing Environment LAN: Virtual Server LAN bound to Loopback adapter for WAN access via ICS
OS Instances. 1. Win2k server: Active Directory PDC running Native mode AD. 2. WinXP: Client 3. WinVista: Client.
AD Users Log on Script: VBS script maps three drives (X,Y,Z) Shared from PDC
Problem... When logging onto the Win-Vista instance with an account that is a member of either the local admin group or local Power Users Group the script fails to map network drives. I have verified that the script is actually running by inserting a couple wscript.echo statements before and after the wscript.mapnetworkdrive statements, while the wscript.echo's come up the drives fail to map. If I remove the users from the Local Admin group or Power Users group the Drives appear at next log on.
Any Ideas?