it really doesn't, but if you try to run the vfp3 app and it picks up the vfp6 resource file, it'll give you a messagebox to the effect that the resource file is not valid (incorrect version of foxpro) and ask you to create a new one.

best if you:

a. install the apps in different directories
b. keep a foxuser (dbf, fpt) in the same directory as the app (or in the base directory)

>They will both be running on the machine. I don't know why the resource file would make any difference to how the code runs.