[bav]

Color up errors are very common. TD's and dealers sometimes get a little carried away and when coloring up 100's, say, also tend to try to remove some of the 500's. So when someone has 15 100's and 15 500's they may grab the 100's 7 of the 500's and give back a 5000. I've seen really good TD's make major mistakes doing colorups that the dealer didn't catch and I was the only player still at the table watching (and yeah, I stopped 'em). And we have the famous example from the WSOP ME last year.

So sure, colorup mistakes happen. Stick around during the colorup if you're adequately paranoid. Outside of the colorup periods, you SHOULD be able to safely leave the table, but do arrange your chips neatly, keep the big ones at the bottom, and don't be late returning.

I was around when someone's entire stack disappeared during a break. The chips were simply gone. They actually held up the event for like 15 minutes while they checked the tapes. Answer: A player's wife did it. He was rushing off to get a snack, or some such, and they were breaking his table right as the break was beginning. So he asked his wife to move his stack to his new seat and took off. She collected his chips, and those of the player next to him which were sitting close (guess the one guy stacked his chips on the right and the other guy stacked on the left?)