Same issue here (safari and chrome), it is forcing the user to restart everything which is quite frustrating.
Takeback action is not working

Hi sitaktif, (and djrem3000) it looks like you both are using the older version of Chess.com. Will you try playing the Computer using the new version of Chess.com? You can find it by clicking on the link at the bottom of any main page that reads: Try the New Chess.com.
This should work better for you on the new version of the site!
Takeback action is bugging and not functioning no matter where i'm trying to use it. Example - "Computer Workout", by pressing the "Takeback" button i can see that the chess piece is going back then suddenly forward and no futher actions, several users were complainin on this, e.x. http://www.chess.com/forum/view/help-support/issues-with-browser-and-workouts
I have tried to use Firefox, Chrome - the same issue.