Jozef,

>My english is not too good, sorry.

It's better than my Polish! *bg* I was in grad school with an exchange student Kryzstof (I think that's how he spelled his first name, it was back during communist rule, so they would not let his wife come to the US while he was here) He never could teach me any Polish, we did a lot of Fortran though.

>I'd like to say that if debuger is activated (in separate window) I can start and quit and build my aplication and all is OK. I can repeat these cycle as many time as I want without any problems.
>If debuger is not activated I can start and quit and build my aplication only a few times, then comes moment that app file is not closed by VFP8.

In your application shutdown code, just insert a SET STEP ON line and trace through making sure things destruct the way you think they should be destroying.

Are you using both VFP7 and VFP8 on the source code files at the same time? I'd be inclined to just copy ALL of the source to a new directory for VFP8 and make sure you recompile everything in VFP8.