Hi Erik:

Here's what I eventually did to get rid of my inability to run my on EXE's

1. Deinstalled Visual Studio completely.
2. Defraged disk.
3. Ran regedit and searched for all instances of "Visual.Foxpro.Application.6" or "VisualFoxpro.Application.6" (without the period between "Visual" and "Studio") and determined the CLSIDs. Then, deleted all references to CLSID 008B6020-1F3D-11D1-B0C8-00A0C9055D74. That corresponded to "Visual.Foxpro.Application.6"
4. Changed value of HKEY_CLASSES_ROOT\Visual.FoxPro.Application\CLSID to VFP5's (0002C401-0000-0000-C000-000000000046)
5. Searched for all instances of VisualFoxPro.Runtime.6 and determined its CLSID to be 008B6021-1F3D-11D1-B0C8-00A0C9055D74. Then deleted all references to this CLSID and the test "VisualFoxPro.RunTime.6.
6. At this point, I ran into a little problem when the registry couldn't delete a couple of references but closing regedit and reopening it made the problem go away. Specifically, I couldn't kill two references to VisualFoxPro.RunTime.6 occurring in HKEY_LOCAL_MACHINE\SOFTWARE\CLASSES\VisualFoxPro.Runtime.6 I'm beginning to suspect that ONE of these Runtimes got in via a dummy project I created and installed for the express purpose of getting the runtime engine in place. I ran it. Later, and I don't remember how much time passed, *something* got crosswired and that's sort of when things starting acting funny. My suyspicion is that the registry got out of sync.
7. After all of this, miraculously, my EXE could run again ... although I had deinstalled Visual Studio completely before I started all of this, VFP6r.dll, VFP6rend.dll and VFP6run.exe were left in \WINNT\SYSTEM32 by the uninstalled. (I would have thought that uninstaller would have taken these out.)
8. Reboot.
9. Reinstall Visual Studio. Reapply Service Pack 3.
10. Checked registry again and the CLSID I manually deleted in Step 3 is back again (008B6020-1F3D-11D1-B0C8-00A0C9055D74).
11. Try to run own EXE's.
12. Life is good again. Champagne starts to flow.

I'm not sure which bit of what madness did the trick, but if this happens again, I'll be sure to try this before biting the reinstall Windows bullet. I've not fully tested every proper working of VFP but am satisfied that this part is done now. If anything starts acting weird, I know I'm on my own. Still, this may benefit someone else. Thanks again for all your help.