Hi Robert,
That is good information regarding sneaking in with MS Visual Studio - I can get various versions via friends in our software engineering group.
Both my machine (good) and my colleagues (bad) have identical new machines with the same base build, and we are running the same worksheet (that I wrote), so the difference is somewhat unexpected.
Hopefully we will be able to try things like swapping our monitors and mice, to see if they affect the driver setup. We'll also get the IT group (they've lock some thing down :-( to check which drivers are in use and if his other software has loaded something that mine haven't (or vice versa).
I'll report back when (if) I have something.
Philip