>Most likely because it makes use of Win9x unique features. Remember that Win9x is still a mixed 16/32 bit OS environment. NT is fully 32-bit and is much more picky. So, for example, apps like Norton Disk doctor for Win95 won't run on NT.
>
>What is the app? What does it do?
>
>Best Regards,
>jmu

It's a exe generated from VFP6 and installed with the disks from the "installation wizard".
Thank's for your help
Michel