first 2 frames x vid

I have no idea what format to use. I have been using xvid cause it looked nice at a small file size ( I need it small for now ). I have used h264 and mpeg.
The question is. How come my renders are now bad on frame 1 and 2 , then it cleans up. If I render jpegs, then sequence, them to x vid or just render x vid, it is the same. I did not have this problem before.
I did get a new ( processor, mother board and ram I really hope that has nothing to do with it)
This jpeg 1600 x 1200 was 33 kb from119