I was playing a 2 | 12.  (this game: http://www.chess.com/livechess/game?id=374439484)  My opponent, gerrylizano, who played white, used the Sokolsky opening (1. b4), which surprised me because I have rarely if ever seen that used.  The game went 1. b4 e5 2. Bb2.  I was trying to figure out the best response to Bb2 since it was sharp/tactical and I had nothing prepared.  I spent about a minute on move 2 thinking, and then suddenly it said game abandoned even though I had about 55 seconds left on my clock!  I asked my opponent and he confirmed I had not disconnected.

Here is what I think happened.  I'm guessing the rules for when the game is abandoned say it's abandoned if you spend over half your time on one move.  The problem is with a 2 | 12, "over half your time" must mean "over one minute."  A 2 | 12 is actually about TEN minutes long, not TWO minutes!  The rule for when the game is abandoned seems to be ignoring the increment.

If this is indeed the problem, please fix this bug!

It is definitely a bug since I just experienced the same problem. www.chess.com - please fix the bug!!