Quick update: we have tested two large installers on three different Win7 Ultimate x64 machines. Minimized the install during the setup process and it automatically restored at the end of the install. We instructed five of our testers to run a setup (minimized) on Win7. Same result -- it worked without any problem. So it's very well possible this is project specific.

As far as I can see from your screenshots, you can reproduce this on your Win7 machine. It would be great if you could send us the project file and the resulting sbevents.log.

Friedrich