Are all of your drivers up to date? What's your rendering preset? Is there an error log if you're rendering with Media Encoder? Can we see a screenshot of your AE interface?
Nobody can tell you anything without exact system info or other technical details such as contents of the comp, comp settings, render settings, cache settings and so on. Sorry, but so far your post is uselles because you haven't said anything that would help to diagnose potential issues. We simply know nothing about your project.
What, exact, version number of After Effects are you running?
Are you still facing this problem? If not, let us know how you solved it. If so, please let us know so we can assist you further.