Why can't I play HD .MOV files on my PC? What program do I need?

Hi! I filmed a few family events with my Canon 14.1MP PowerShot Digital Camera (SD1400IS). The videos are in HD and in MOV formats. I copied them to my computer but I can't seem to view them. On quicktime, I see a green screen and can hear the sound of the video but I can't see anything. VLC and WMP doesn't work at all. I even tried windows movie maker but that was unsuccessful too. What should I do? Is there a new program I need? Thanks