OS and AE version down to the last decimal point please. Also, if this ever worked, what changed? If this happens only when you are working on complex comps we need details.
Thank you Rick. Sorry for not including that. I'm using Windows 7 Enterprise with After Effects CC 2015 (version:13.5.1). It has never worked. I've used the other applications on the suite such as Illustrator, Photoshop, etc. They work fine after launch. I haven't created anything in AE on this machine yet so it's an empty project. I can't even start importing images/videos before it starts to freeze up.