Microsoft, I was wondering why you don't let us do this? Compatibility options are set in the Registry with a value called "path to file" and data of the compatibilty option.What difference does it make if the file path is something like "C:\TEMP\My.Msi" or "Z:\Installs\My.Msi" where Z: is a mapped network drive?Some of our very old apps run off the network and it's no use having compat options that you can't set...