hi, thanks for answer. 1. I did not get any visual errors, I've got only strange behavior of the windows on screen. I set for my window TOPMOST order, but in OS it actually appears under any current active window on the screen. 2. I use VC2005. I found some interesting topic on this problem: http://groups.google.com/group/microsoft.public.vc.mfc/browse_thread/thread/8c9333777d461126/c5ee093565701048[^]