Qt designer stoped working

[DrageFabeldyr]

Hi, i have the problem - i moved whole system from my work pc to virtual box
and after that qt designer stoped working - i can't add anything to my form and can't change even size of "views" also i can't move elements on my form and change form size by mouse

the other problem - i can't re-install the whole qt cause when i try it i get a black qt window when i try to open or create some project
as i realized - it's because i use an old OS - Debian 6.0.10 but i can't use newer debian so is there any possible solution of my problem?

for example - is it possible to re-install only qt designer?