I have an MPG movie that plays fine on WMP, but on Pr6 it shows all kinds of artifacts, green screen type things - the properties are MPEG 720X480 29.97 48K total duration 2:04:56:00. If I click the File, and do open with, WMP works fine, QT gives me error 2048, Movies and TV works same as WMP, that is, video and audio play back. So far, I made a much smaller clip of 5 seconds, tried Nesting it, and no joy yet... If I go directly to the file in media browser and click Import, it proceeds with no complaint.
Try updating or rolling back your graphics driver directly from the video card manufacturer’s site. If NVIDIA, do a clean install.
You may need to use an old driver for CS6.