I think you will find an answer here:
http://forums.microsoft.com/TechNet/...3838&SiteID=17
"Joe" wrote:
> We map drives using a VBscript assigned by a GPO. With our test Vista
> clients (including RTM Vista Enterprise) the drives are not mapping. I can
> see it running the script (logs to the eventlog) yet the drives do not
> appear.
>
> Does anyone know what has changed in Vista to cause this?
>