problem with xv using extern_disp

Hi.

I m using the new driver with xv support on mylaptop (SOny XG18) which has an 
NM2380 chipset. I have been trying to get xv support to work in MPlayer and 
couldnt figure out why it wasnt. i get white horizontal lines across the 
screen but no picture. But when i remove extern_disp from my XF86Config file 
it works.

Has anyone got any clues

Thanks

Daniel