Computer specification and program version, see this topic for what is required and please quote processor and graphics card make/model in full - I would suggest you put this information in your profile signature so we do not have to keep asking for it.
Are the graphics card drivers up to date?
A screen shot of the Program settings, Device options tab would help.
Download and install MediaInfo and analyse one of the clips and post the results, see this tutorial on how to setup MediaInfo and analyse a video clip for all the data required.
Thanks for the computer specification - we still need the MediaInfo data of one of the clips that causes the screen to turn black and the Program Settings, Device options tab screenshot