Check the actual error in the Event Log.
We have been developing/compiling with PB 11.5 in numerous Windows versions (including Win8 64) and deploying our apps to hundred PCs with numerous Windows versions as well (XP included).
We have no problems concerning compatibility between Wiindows.
Are you explicity using AppData, Roaming and other Vista/7/8 folders?
Are you sure you packed all the PB DLLs needed in the correct version?