Hi, Daniel -
Does this happen for all applications, just one, or some but not all?
What happens if you create a new, quick, throw-away app that say, only opens a window that contains a Close button?
If you're experiencing this issue with only one app, that may indicate a problem with a PBL or a faulty migration, as Chris indicated. If this happens with multiple app's, I suspect you may want to try to uninstall/re-install PowerBuilder, then re-migrate your app to the new PB version from a backup copy of the pbl's.
Regards, John