when i render my movie, it will freeze and random spot and will stop dead,

for example, it will render to 78% then stop, but the elapsed timer will keep counting, when i watch the footage that it rendered, i can watch everything up to were it stopped.

the footage is of call of duty 4, there is a video timeline, audio timeline and a generated media timeline.

please, help me fix this problem as i have been working on the movie for many months and i do not want to lose all ths hard work