Shutdown time will vary depending on the programs you are running or have run. This is common with all windows machines. I wouldn't worry about that too much. An extra couple of minutes won't harm your car or it's battery. If your computer is not turning on the Opus may be giving you an error, check the tiny little LED on the power in edge of the board and check the error table on the instruction sheet. Maybe you've already done this, but I didn't see that you have.