Quicktime Screen Recording Freezes Computer

For a while I've been using Quicktime on my Macbook Pro Classic 2012 (OS 10.8.4) to record my screen. But for some reason, recently it has begun to randomly cause my computer to freeze up. And by freeze up, I don't mean spinning beach ball or kernal panic -- it literally FREEZES, as in, all of the sudden everything onscreen stops, the mouse won't move (but remains a pointer, not a beach ball), and all sound stops. Closing the lid, pressing escape, the mouse button, etc. does nothing--the only way I can get out of it is to hard shut down by holding the power button.

Any ideas or thoughts on what's causing this, why it might have only recently started or how I can fix it?

BTW, my MBP is currently using a Crucial SSD that I installed myself right after purchasing it, if that matters. Also I've been recrording larger things lately, so perhaps that has something to do with it?