Bug in Qt or Qt Designer or my mistake?

[[maTa]]

Hello, I am creating application MDI based and somehow it behaives strange. Developping in Qt Designer, I dont write code much in the source files and it causes some strange error when I activate one of the forms in my project (Form3 actually):

*** glibc detected *** corrupted double-linked list: 0x080d1ea0 ***

Quiting the application.

The thing is that when I put Grid Layout on Form3 with all elements included I get this error, but when I regroup them with vertical and horizontal layout it is not present. Also the Table on Form2 behaives like fixed, when Form2 maximized I dont see the Table on it also resized...

I share the source with you if you can help me...

Using:
Qt 3.3.4
KDE 3.4.0
Fedora Core 4

Thanks in advance...