buggy garphics

[kolijoco]

i'm running the game o GeForce FX 5650 Go (Win XP SP2), and having strange atrifacts (seemingly they're flashing, vibrating streaks of polys extending from characters, even my own)... no i do not have problems with any other games, my direct x seems to run fine... does anybody have any idea what this could be?
any advice would be greatly appriciated... thanks!