Game only works 25% of the time.

[calmlikeabomb42]

i have this game on steam. my specs are - Asus M2A-VM, Athlon X2 4000+ 2.1Ghz Overclocked to 2.62Ghz, 4 Gigs of DDR 667 XP says 3.25, Nvidia 7950GT 512MB.

 

when i open the game most of the time it will just keep loading and loading after i hit start game. the characters will keep coming up and the music will eventually end. sometimes i get into the game and all the models are clear, other times i can play for 2-25 mins and then it will start freezing and changing frames every few seconds.