Johnny, thanks for the reply. No, I don’t think that applies to this machine, I booted up with the 3rd party signed driver and it booted up fine, it’s when the driver isn’t signed is when the machine won’t boot. If I delete the file, no problem. However, the issue that shows that is slightly more than annoying is that once my application uses this driver, then that driver won’t be reloaded with a new installation of my application. The file can be overwritten, so that’s good, but I have to reboot to test it. I don’t do this often, but I was making sure that I could reproduce the customers issue, and I built my installer without the signed version of my driver, and my file still work. I think this is a result of me “installing” it with the INF file - this doesn’t occur with other machines.