>...Disallowing writes to the HKEY_CLASSES_ROOT ...the entire OS breaks, since key elements of the OS rely on COM and OLE information contained in this section of the registry.

So, it is not really an option (although sometimes users seem to be happier when the computer breaks down).
I guess I'll have to look at using a registry class - I've downloaded Rick Strahl's - to remove unwanted keys. I hope it (the registry class) knows better than me what it is doing. I'll have to decide when, or how often do I want to do this 'clean up' too. Do you see any practical advantage in VFP registering let's say .scx files - I know you can double click and start VFP and open the form, but do developers do this?
Thank you for insights.