Tactics Trainer Error

While doing tactics, it shows "incorrect move, you got 1 (or 2,3...) out of X moves, try again" in red. Then it shows "correct move" in green. Normally after a few moves, the screen goes white with some weird code at the top, which is shown in the following picture.

This has happened a lot. Anybody has the same problem?

You can view the image in another window.

Do you get this error on all tactics or just certain ones? When did you notice the problem start? What browser/operating system are you using?

On some of tactics. This problem started at least half a year ago. I've been using Firefox.

Can you please let me know what tactics you see it on? (You might try checking your recently completed tactics.) Have you tried it on any other browsers?  

The tactics with such errors have never shown in the completed ones. Whenever an error hanppens, I can only go back, but a new one will start. Next time I will try to get some info about the tactics with errors.

I haven't tried it on other browsers. Maybe I will in the following days.

It also happened on google chrome today.

happened to me :P