Hi,Lutz

Thank you for your kind reply.
Of course, I don't directly assign numeric value for DATASESSIONID and
don't change sessionid in the method, except in Destroy method to comple-
tely close all tables in the session just like..
...SET DATASESSION TO Thisform.datasessionID..
This form's class hierarchy is 3 level deep and above code also implemented
at parent class's destroy .
As you suggested, I checked all variables whether it refereced form object once
and not released on destroy, but no reference was made.
Finally, i checked with _screen.forms collection at calling forms activate
after called form's release, as you know _screen.activeform is still usable
before other'foms activate or show method, and i saw THE FORM was released.
However, when i opend it one more time the called form's datasessionid starts
from +1. Let me tell you the order i did from the start.

1. dispform open -> sessionid says '2' (1,2 used)...normal
2. open concerned input form(named inputform) by click of dispform's cmdbtn
3. dispform.hide()
4. inputform's init -> sessionid says '3' (1,2,3 used)...normal..
5. inputform release -> _screen.activeform is still effect, not completely
. removed form memory yet....normal
6. dispform's activate -> total 3 session is open(1,2,3 still used)..normal.
7. befor dispform's cmdbtn.click()..-> total 2 session is open..(1,2 used)
. inputform completely released.
8. open inputform again -> next sessionid should be started '3'...but..
9. inputform's init() -> sessionid says '4' not '3'..
and VFP crashed,closed and returned to Windows.

As you told me to check datasession window, but i can't make it enable
on my menu though i added it into menu bar. is there other way to call it
in the code ?
I think there is still some trouble in datasession though form has been
released. I also would like to know crashing is normal VFP action when
datasession goes wrong.

Other same kind of forms goes fine at the same senario but why this form..??
Any advices would be VERY VERY appreciated.

RGDS
HK.Lee