Problems with graphics / running program

We are working on an Imac (mid 2011), with Snow Leopard and Parallels with Windows 7 Home.
All programs are running well but there's one software losing the input fields randomly. The Software is "Haufe Immobilienverwaltung" a program to manage real estate. We installed Bootcamp and Windows 7 on the same machine and it works without any problems.

We tried all different viewing modes for parallels and different monitor solutions as well as different settings in the configuration of parallels...

here is a screencapture-link:
http://vimeo.com/33607769

maybe anyone knows something ...

thanks