>The application is installed from VFP6.0's set-up wizard package. It is an .exe accessing a .dbc in a subdirectory. Is this enough?
>
>Paul

Paul,
You may have tried all these or asked yourself all these before but I'll ask anyway:

Have you checked to make sure that the setup was run successfully on those PC's and that the 6.0 runtime was installed by the setup in the system folder?

What may be in the folder that could cause a problem that the setup wizard is using to get your executable and subfolder containing the tables and DBC?

Are the problems consistent and repeatable?

Have you tried uninstalling vfp5 from one of the problem PC's and run your program?