Qt release conf problem

[make]

hi! I am not new to Qt, and usually i have not any problems with it or just solve them with documentation. But now i have a bit strange problem.
First i should say, that use Qt with MSVC2010 compiller. I have an app with 2 QWidgets (so with 2 ui forms). So in first widget i have a button, and when i push it, the second widget must appear. To initialize second form i use:

resWidget = new QWidget();
resUi->setupUi(resWidget);
resWidget->show();

resWidget = new QWidget();
resUi->setupUi(resWidget);
resWidget->show();

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So the problem is when i compile this app with debug configuration - all works good. But built with release configuration program stops working after pressing a button in the first widget. I debuged the app and the problem was in the line with "setupUi(...)" function.

P.S. One more interesting thing - if the second form is empty - it also runs good in both configurations.