First I wouldn't render an MP4 from the render cue -- ever. I'd use the Adobe Media Encoder.
Second, without details about your composition including effects, source footage frame size, and 3rd party codecs that you may have installed we have no idea what may be causing your problems. With standard effects, standard source files and standard render settings rendering with only 8GB of ram won't be very fast but it should work. You've got something going on that isn't standard. Tell us what that might be and maybe we can point you in the right directions.
So I tried to Render with AME and for some reason it worked for like 5 minutes of rendering and theen it fails with the error : Error compiling movie. Unknown Error. I searched google and tryed everything i could. When i select to render Only video it freeze so it has to do something with the Video. It is like 10 frames into the composition where it fails.
You have very little RAM which is likely to be causing your crash.
Reboot your machine. Start no other software but AE. Then render to an intermediate file format in AE (with multiprocessing turned OFF). A good intermediate format would be QuickTime with the PhotoJPEG codec. Then, close AE and take the resulting .MOV file into the Adobe Media Encoder and create your H.264 from that.
If that doesn't work, tell us exactly what happened.