Issues with captured footage from a Panasonic GS500

Hi I have a Panasonic GS500 MiniDV video camera and I have been filming with it and capturing footage off it for more than a year. I use Windows Movie Maker to capture the footage normally.

Normally after I capture the footage the captured file plays fine smooth playback with good quality but recently the video files I playback are extremely choppy and my existing video files that played perfectly before now also play choppy.

I suspect it is a problem with the codec that is playing the file (Type 1 Microsoft DV right?) If you guys could give any advice it would be most appreciated as this is over 9gbs worth of footage. Thanks