it's good that you found the culprit. now you can pre-render the offending comp using a production codec (Animation, PNG, PNG Sequence if you need 10 bit) and replace the original and move on.
if you are set on trying to maybe fix this you can try:
1. Render your desktop - see if that works
2. empty cache (edit->purge->all) and in the preferences under Momory and Disk cache - 2 options
3. reset your preferences: cmd+alt+shift+lauch the App and click o.k to reset preferences.
4. that's all I got for now
I found out what was wrong and it was pretty simple. I had a 500 frames long sequence in my composition but frame 25 was missing and thats the reason After Effect could not render it without the error. But thanks for the reply.
Good job. finding the offending comp was the way to isolate the problem, then the frame.