It could very well be a memory issue, if there isn't enough memory per core - I can see it failing in the wasteland of virtual memory.
It would be interesting also to see if instead of rendering a movie file, if you rendered sequential stills if you still get the same problem.
I've had some wierdness in rendering like you have had - and it was project based. I resolved one issue by starting a new project and importing the old one in to the new one. Not sure why, but it fixed it.
I know in the old days, clearing the preferences sometimes would fix misc issues.
I've got 4GB per core so I don't think it's a memory issue. I also tried rendering to avi and a png sequence. All failed. I'm thinking it's codec related. I know what you mean about importing the project into a new one - that's definitely helped in the past - I'll try that now. Thanks for the response.
Sounds like CODEC related. Worst case scenario you can convert the source footage to another format for comps, then finish with a converted uncompressed - but depending on length, that could be a nightmare sized file.
Not sure if you've tried Nucleo Pro 3, I've had pretty good success with it as a part of my AE workflow, though quite honestly I haven't tested much in AE5 (I'm still upgrading my plugin library before I go into full deployment there)