For some reason vids in 2.7 downloaded onto my PC will not play. Gives an error message. Vids in 1080, 720 no problems. I am running firmware 1.2.40 and Go 3.1.1.

In the camera setting for the GO APP do you have the video file type selected for one your computer can decode?  There are two file types .MOV and .MP4  Most computers can decode .MP4 files and if you install Apple QuickTime most computers will be able to decode .MOV files.  The .MOV file format is an Apple proprietary file structure.

On top of what JackA provided, your computer might not be powerful enough to run 2.7K footage. Are you able to try a different computer? What kind of video player are you using?