Using windows 7 64 bit with a geforce GT 335M

Ok, here it is:
I bought MDK installed, played and the game worked just fine, just with the texture glitch that was mentioned in this foruns a couple of times.
But I am in the end of my semester in the college so I wanted no temptations, uninstalled the game and deleted the installer.
Not resisting the temptation of playing it again I downloaded again and installed again, played a little and then I resisted and end up deleting the game again.
The thing is, in the third time installing the game, now it has a problem, the game doesn't launch everytime, I have to set a compatibility mode for it and then turn the compatibility off so it launches right and once in the game it has a problem with the textures that it makes the game unplayable. The game slows critically down when start loading textures, even when you just do the graphic test in the options.
so... anyone has any idea how to solve this?