HI, im wondering how i can fix this problem, if i play with no sound game wont stop, if i play with sound (if i put on as playing on windows XP SP2)

the game just stops, and i cant get any further than olympus heights, trying to get to apollo square and nothing happends, shall i put down the graph a bit, im running all in high and direct x 10


im using:
Windows Vista Home Premium SP1
GeForce 8400 GS 1023mb
2048mb DDR2
AMD Athlon 64 4000+x2



so what could the problem be??