50hz / 60 hz problem

[OWA]

hey pplz, i have my pal dreamcast that i run copied games on, the problem is that i run my dreamcast ion a tv tuner card, and when i run a game if i get a choice between 50 hz and 60 hz then i have to choose 50 and things will be fine, but if i dont get the choice and the game runs at 60 hz then my screen comes out squished and blurred at the bottom, i was wondering if anyone knows bout anytyhing i can do to fix this, or maybe files i can download from here to boot correctly? anywayz thnx y'all peace