It is unusual that you should be running into this error with any frequency. And Mavericks doesn't have the issues that Yosemite has, so you should be doing fine. Lots of people are running AE CC 2014 on that OS with no problems. The more techy folks on this forum are going to need lots more info in order to help you.
For example, when does this happen? What effects are in the composition? What footage/assets are you using? How long has it been doing this? Do previous versions have this issue? Etc.
This is happening every time I try to do a RAM Preview. It's happening with all of my compositions (motion tracking, radial blur, cc toner, a bunch of masks). I'm using action essentials 2 and various downloaded sounds and images. All of the camera video is dynamically linked from Premier Pro (8.1). It's been doing this for about a week. This is the only version I've used (just got it 2 months ago). 5g of my 16g RAM is designated for other applications. Hope this information helps. Any ideas?
Try creating a brand new project, creating a new comp using the 1280x720 preset, creating a little 200x200 solid, keyframe a simple position move and RAM preview that.
Does it work?
If so, try a project that DOESN'T include any dynamically linked Premiere projects, but does include footage.
Like, import a Premiere project using the Import Premiere Pro Project menu option. It will bring all your Premiere Pro sequences from that project in as compositions with each edit on its own layer. Benefit for compositing and color correcting since you have single shots! Try RAM previewing that.
If it works, great; you've found a new workflow! If not, describe in detail the format and codec of the offending footage.