A couple of weeks ago I posted a topic about the Preview Screen of the Roxio Game Capture HD Pro Software flashing/flickering and being distorted.
A fix has been brought to my attention by a YouTube user by the name of TheAsine.
Provided that you have checked the cables, software updates, video and sound driver updates, windows updates, and virus scanners have been used. This may be the fix for you.
Here is a video I made explaining how to apply this fix.
Thank you to all that tried to help and I hope this works for you.