Pink edges on rendered movies
 

Hi - I'm experiencing difficulty in getting clean renders on a 7 minute video.
At first I thought it was just the smaller versions but have had some on HD renders as well now. It gives me random pink edge on one side of the video (right), sometimes this is thin ie a few pixels wide, or it can be up to a tenth of the screen area, sometimes it's a flash, and other times it's there for a few seconds.
It happens more when rendering at resolutions below 1280 720
The system is Dual Quad Zeons, 16 G Ram using Cineform AVI with MXO2 mini (not Max) rendering to H264
Anyone else seen this? Any ideas?
In the meantime I'll just keep rendering them out and hope I get a clean one.
Thanks
Billy