>>>Interestingly if I include CLEAR PROGRAM in my Main.prg on the way out while shutting the app down, it works ok, just as if I issued it from the Command Window. Ok, a workaround ... but I want to know what and why in case it comes back in a more malevolent form or time. :-)

Update: there's a new vfp6 SP3 "caching" bug reported in the 1/00 FPA that sounds like it might be related to your problem. It's in Malcolm Rubel's article on Run-time Compilation in the "Now the Bug" section - I thought of your problem when I read it - check it out, if you can.