MPEG 1/2 (MPGV) Codec? MPG movie won't play in QT

I have been given several video to encode, however, I cannot view these source videos in QT or in MPEG Streamclip. In QT the screen is black with no audio and in MPEG Streamclip the screen is white with no audio. This makes me think that I am missing a codec. I can open the videos in VLC and when I look under "Media Information" it tells me that the codec is MPEG 1/2 (MPGV). I have searched online and haven't found anything. I have the MPEG 2 component, I have Perian installed (it's installed twice, not sure if that is a problem), I have all the ProRes codecs plus many more. I am a video editor, so I have a lot of different codecs on my machine. Could the combination of different codecs be an issue? I tried opening the videos on a different machine (which has the mpeg2 component as well) and it didn't work. Can anyone help with this issue? I'm going crazy over here!