Thanks spastor. I believe the problem is sorted now given your answer. It was actually a problem running cmd.exe.
The reason I was getting problems is to do with permissions. In the course of trying to figure out what was going on I have discovered that Windows has some 'magic' user groups - one being INTERACTIVE, another being BATCH.
It turns out that by default, C:\Windows\System32\cmd.exe has Read & Execute permissions set for Adminstrators and INTERACTIVE by default (no BATCH).
Therefore - I think that anybody out there who is NOT getting a problem running QlikView as a scheduled task is running that task using an Administrative logon which is what I was trying to avoid.
You can use VB-Script to reload your QVW - look at this sample:
Option Explicit Dim qv ' As QlikTech.QlikView Dim qvDoc ' As QlikView.Document ' open QlikView application Set qv = CreateObject("QlikTech.QlikView") ' open QlikView Document Set qvDoc = qv.OpenDoc("c:\test\test.qvw") ' reload data qvDoc.ReloadEx 2,1 ' 2=ignore Errors; 1=hide process dialog ' save and close document qvDoc.save qvDoc.CloseDoc ' quit QlikView qv.Quit Set qvDoc = Nothing Set qv = Nothing