Take a look at the attached video link. I'm using the ZWO ASIair Pro and a ZWO ASI 120mm Mini as my guide camera on a William Optics 50MM Uniguide Scope. The 120MM Mini works great for about 40-60 minutes and then this happens. Any ideas? https://www.youtube.com/watch?v=YDl7ylRKl9I&feature=youtu.be