Quiz trouble

Hello there,

I am trying to fix this problem: my course (SL2) is ending with and evaluation form, a 15 multiple choice question quiz. 

Sometimes the quiz is working, sometimes it doesn't and all you have to do is to exit and enter the course again. And then again ... could work or not :).

Have you ever met this kind of problem? Do you have any idea what to do, or to check, or to ask my LMS provider or my IT department?

Thanks in advance,

Irinel