What is the exact version number of AE that you're using down to the last decimal?
Have you cleared all the caches?
I am running 2015.0.1 I cleared all cashe today....it's better.... but still seems to show up sometimes in a quick preview.
I am working in another project that doesn't seem to have that problem. Sometimes I have 4 different projects I am working
on during the week. I am on Mac 10.10.4 2.6 GHz Intel Core i7 MacBook Pro (Retina, 15-inch, Late 2013) NVIDIA GeForce GT 750M 2048 MB 16 gig Ram
You should consider updating to the newest version of AE or going back one version.
The newest version is 2015.1 (which is AE version number 13.5.1)
Alternatively, you could try using version 13.2 (AE CC 2014). The project files are backwards compatible, so you can just open them up and keep working.
AE CC 2015 is the first step in a major rewrite of AE's underlying architecture, so there are still a few issues with it. If updating to the latest CC 2015 doesn't cut it for you, try dropping back to CC 2014 and see if it behaves.
Any update or resolution for this issue? We are seeing the same thing randomly on 1 of our 10 edit bays. (Windows 8.1, AE 13.6.1 (2015.1) on HP Z800 w/ 48GB RAM, using Avid ISIS shared storage for media and 250GB SSD cache drive.)