More Detail. Recently installed Full Master Collection Suite CS6 PC version into a brand new PC with 64GB Ram 4.5Ghz CPU on a ASUS Sabertooth X79 m/board, GeForce 680 graphics, SSD for programs and 2x 3TB HDs for storage. Very little other software, not even Office as didn't want to effect video editing. Don't use internet so can't get virus attacks, so haven't done an update unless I did one at install time which was a few months ago.
I record with JVC-GY HD 100 and 250 cameras which record on mini-DV tape and Hard Drive which I import as MT2 format. I'll do some tests but I think the audio slip is on both MT2 files and tape captures alike.
Never had this problem with previous verions of Prem Pro such as CS3. It clearly gets effected drop a frame drop occurs, I get a RED frame and half of another nearby frame corrupting a frame quite often even on brand new tapes, that usually instantly un-synch's audio by a second, but even when I haven't spotted a dropped frame it creeps out of synch after a few minutes.
I get a RED frame
Those are inserted by PP when there is a drop out of tape. The red frame is there specifically to combat sync issues, so I'm not sure why you still have them.
In any event, at this stage of the game it's better not to shoot on tape if you have other options.