Ray, yes, Installshield runs your Custom Action in a temp directory. The solution is to call something simple that will shell to your executable. That will run your VFP .exe successfully as a Custom Action. We created a C++ .dll that simply calls a CreateProcess, but, you could also use COMMAND.exe or VBScript...
>Using InstallShield Express with a Custom Action for a post-install vfp 7.0 executable. When the .exe runs from InstallShield I get a Foxpro error "msi6231.tmp not found." Running that executable manually after exiting the installer works just fine. Anybody seen this or have any ideas?