final cut pro 7 helo

hello people i have a problem with fcp7 when i render a short video that has gameplay and facecam but when i render the 3min video i get a weired black screen when i view the video to its end i always get it but when i used a 6 min video it extended it to 10 mins for no reason is there a fix to it




mac specs

macbook4.1

osx 10,7,5
ram 2gb
160gb hdd