Vassili,

>WinWord instance was manually closed before form is unloading.

By this do you mean you are clicking the X or doing a File/Exit command from the Word window?

>And all object references were assigned to local variables in separate procedure. After form finished 1st time there are 2 data sessions: default and Unknown. Second time another Uknown DS appears.

This is a real indication that you've got object references hanging around. Have you looked in TaskManager to see if Word is still running? Word is really bad about leaving instances running if you don't properly disconnect everything. I know when I first started playing with Word automation that I ran into out of memory errors at one point and sure enough I had like 10 instances of Word running at the time. After that I got in the habit of explicitly setting every object reference = .null. when I was done with it, and calling the Word shutdown sequence when I was done with Word itself.