Hi Nadya,
Two ideas:
1. Double, no make that triple :) check your SET PATH setting. I recently had a similar experience to your's and there was a bad path in the SET PATH setting. I only discovered this after manually copying and checking each path in the SET PATH setting.
2. Is there anything flakey in the form's DATA ENVIRONMENT? I normally don't use data environments, but I recently came across a form where the original developer used the Grid Builder which "secretly" added a bunch of tables to the DATA ENVIRONMENT. We didn't discover this until we tried running the EXE outside our dev environment.
Malcolm