Hi Gabor;

  I would guess that in this particular App, it's checking to see if it's running as a compiled EXE or running as a sub-task underneath the PB IDE (ie: PB220.exe). My guess is that it might be expecting PB125.exe and if not verified as such  - puts out this message. The best way to verify this (IMHO) would be to run the App via the IDE's "debugger" and follow the flow of the code to where that related MessageBox command is performed. 

  Also, you could use the IDE's "search" feature to see if it has any code that compares the text value "PB125" or "the running module" part of the message and where that code could be found.  HTH

Regards ... Chris