terrible video quality after upgrade

Hi,

I recently upgraded my storm1 from .328 to .484 /758 Hybrid. I am happy with it. speed increased noticable, but Video quality is terrible. I watch a lot of DivX on it, so it is a real problem for me. There is a lot of blocknoise in the video, you know this maybe from bad burned Video CDs. Seems this also varies with temperature and is defininately a OS bug, because half of the movie was fine and after upgrading the second part was jerky. Is this a known bug? any solution?