Ken's right; for this particular app I zipped-up the runtime files into my own distribution file with my own install routine - precisely to get around some issues relating to changing users' systems. On all machines (well over forty) except the three lap-tops this worked just fine.

For what it's worth, Rich Simpson correctly identified the problem as being an out-of-date OLEAUT32.DLL file in the windows\system dir. And even though I spend considerable time researching the problem, I could not find any mention of this problem (including on MSDN and in VFP doc).

Thanks for the input,

-Arne