i have a seemingly simple project that is causing seemingly random render problems.
i am running top of the line MacPro, Yosimite, AE CC 2014. its a simple 2.5D comp with video and still assets.
thought i may have overcome the problem by shortening some file names - i recall this having an adverse effect in previous AE version, but no joy.
For weird technical things like this, we will need tons of information. Is it CC 2014.2? Do you have ray-traced renderer turned on in your comp settings by accident?