Blurry video in 2.51
 

Hi
I upgraded from 2.43 to 2.51 and the video is blurry now. i tried all renderers in video options, but the picture quality seems lower than before. after the first load i got the not able to use switching to EVR renderer message. I have an nvidia graphic card, 2.51 version and vista home premium 32bit. How can i increase the video quality in bs player?
new codec pack?
thanx