Sounds like a video driver or abstraction layer issue. The app is having trouble "repainting" for some reason. There are a few properties one can tweak on the VM to control how it uses DirectDraw and other 2D and 3D drawing APIs. First, you should make sure your video driver is sound, and DirectDraw is current.
This started when I upgraded to Win7. It was not seen before! Firefox, Openoffice, Notepad++ and Arduino 0.22 all work correctly with Win7.
Different OS means different 2D and 3D driver abstractions that Java depends on. OpenOffice might use different 2D/3D settings, or a completely different set of widgets. Notepad++ is a native app, so this data point isn't really relevant.
Did you check DirectDraw, etc.?