Tactics Trainer Buggy - Automatically Resets Itself

Browser: Firefox - whichever is the latest version - currently 31.0.

I've noticed this many times before, but it would usually be a rare occurance. However in the past few days, this has been happening daily.

A typical example: I make my move and the board resets itself to the starting position, although the timer is still moving and I cannot move the pieces anymore. There are times when I make the right move, the alert changes itself to the red-coloured 'wrong' move, but seconds later 'corrects' itself to green. Even if it's an actual wrong move, the resetting happens when I try the puzzle again (without points, of course). If I refresh the page, a completely new puzzle comes up. It's completely maddening!

It's starting to happen again. Very frustrating.