I'm not sure and i'm plagued by it as well, however its happens when under cold and when i'm barely stable enough to get a capture...........
Rules are rules though " A VALID CPU-Z screenshot"
I can't submit mine either I've preety much nailed it down to the rejections happening due to a variation in clocks........F7 4950mhz..........ends up being 4970 in validation...and rejected, downclocked to 4.0 and validated and it passed.......
Example.....I can't submit this, looked preety stable to me though
http://valid.canardpc.com:80/show_oc.php?id=527275
screenshot
http://members.cox.net/bostonreefer4/7204core5.0.jpg