Does the system turn off or does the skp file disappear? My guess would be that your system has an Intel integrated graphics adapter. Many systems with this display card setup seem to run into issues with SU particularly when running the 64-bit version.
Try uninstalling the 64-bit version and replacing it with the 32-bit version, This, hopefully, should stop the unwanted performance. Admittedly it would be preferred to operate the 64-bit v because it is purported to be faster, but I have had to resort to this “fix” in my case as well and have not seen a noticeable difference in performance.
You can read more about this issue at the following link:
SketchUp and Intel HD Graphics 5500