i haven't this problem but now i don't know about that!!! when i chang a value or handle the time line or set an effect and other things mabye, it go to take a preview of my project and at the end it want to save that, but this problem sometimes will be happen and sometimes won't happen. i thought that my keyboard keys are sticked and i changed my keyboard but the problem still was there. i go to my prefrences but didn't find illegal option. i somebody know about that tell me please!!!