The computer specification you have posted is incomplete, what is the graphics card installed - full name and model please. I would suggest you put these details in your profile signature.
We also need the program version number as found under Help, About in the program, the video file format and details of what the encoders used for the video and audio streams - to get the video file information 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.