Version Tutorial Freezes

I’ve downloaded this version and going through the tutorial. I have managed to crash it several times. One repeatable step is to attempt to view the PDF under ‘spacewalk_info’ and while viewing it move to a different section of tutorial. I also had a problem going to the video ‘ThisIsBuzzAldrin’ which froze the tutorial. I’m using Windows 7 on a stable computer that seems to be running everything else quite nicely.