Empire total war just exits out...

Im playing empire as india and have like 35 cities and its 1758, i click next turn and it goes fine till it get to swedens turn then the game just quits and goes to the desktop. It just completely exits out of the game!!!! Ive tried several times reloading the auto save, even going back a save, and the same thing still happens in 1758 when its swedens turn!!! I tried lowering the setting to medium, bo change. Im playing at 1920 1200 with max everything, 8xaa, hdr, ssao etc with a i7 920, 6g ram, and hd4850 1gig with vista 64bit. I dont know if its the video card or some error with vista, if it is or isnt can some1 help me please!!! its never done anything like this before.I really dont want to never finish the game!

it might be an issue in the game files

ok i checked and its updated completely. I just baught it a couple of days ago. If it is a problem in the files how do i check? im not very computer literate...