>>>Hi Beth,
>>>
>>>The solution was simpler. I had a "wrong" line in the sub-application that was setting Path to different folders. I guess SET PATH is not session specific and when the control was returning to the Main application was not finding the libraries. Once I commented the SET PATH line, all started to work.
>>
>>There is no "session" when you DO whatever.APP, it's really no different than running a .PRG. Same is true of running an .EXE with DO.
>
>Let me clarify. Say my .APP has a form that sets CONFIRM ON. The form is in Private Data Session. When control is returned from the .APP to the main application, will the setting of SET CONFIRM be ON or OFF (default in Main program)?

It depends on is this setting scoped to DS or not. There is a link in the Help file talking about scope of the settings.

Here is a link for SET CONFIRM:

http://msdn2.microsoft.com/en-us/library/4700aty2(VS.80).aspx

So it is scoped to DS and your main session is not going to be affected.