The green chunks definately sounds like a codec issue. There are several codecs that are supposed to be compatible with the MPEG-4 ASP standard and they often try to play each other's videos, but they're not very good at it. This clash is very common between the Divx and Xvid codecs. Often one will override the other even when the right codec is installed on the system.
First, check that you have the latest versions of the Divx and Xvid codecs. If not, uninstall the old ones before installing the latest.
Once you're up to date, open up the configuration tools for each codec, look around and you should find an option called "fourCC support" or similar, with tick boxes for different codes. Untick all except the native code, which for divx is "DX50" or for xvid simply "XVID". This should stop the codec trying to play anything but it's own videos.
_________________________
"If I were a guy, not swallowing would be a deal breaker. So what if you cook and clean? I can get a maid for that." - Gia Jordan