Ok... After Effects CC 2014.
Recent updates installed.
Windows 7 - 64 Bit
I'd say the hardware is not important because I could reproduce this on about 5-6 different machines.
Steps to reproduce:
1. Import footage
2. Render Ram preview
If you don't have Service Pack 1 for Windows, you should get it. No guarantees, but it may help. For the moment, I'd just wait until the 3D renders are complete before importing... there isn't much else you can do at the moment, anyway.
There's only one application I've seen that can reliably, "works-every-time", read media files as they're recorded: Avid Newscutter...but then, it was created to do precisely that. AE wasn't.