It installed in only a few seconds
My best guess, and that's all it is, is that it wasn't really ready to run when it prompted you to run it. Perhaps the drive had not quite finished the physical write process, or the Registry was not completely updated.
That error typically has to do with user permissions and normally means the program has to be run by an administrator. So perhaps that was where the initial delays were. If you get the error again, you may have to ensure you run it as an administrator.