You should at least try using another browser to see if the problem is with chrome or chess.com. My blog might help out here and if not I'm guessing this is one of chess.com's many random and temporary glitches, but if the problem persists contact the staff directly via Help & Support at the bottom of the page
http://blog.chess.com/NimzoRoy/diagnosing-and-fixing-internet-problems
With google chrome I am unable to make my second move in Chess mentor and am forced to click free next move.
Am I forced to change browser which would be very annoying?