Preview slow and choppy all of a sudden

Hi guys,

I've never had a problem running After Effects, until recently...

Before, I was able to preview in the normal fashion.  The green bar would do its thing, load, and then allow me to preview my project in real time.  

Now, all of a sudden, I'm unable to do this.  Now all I see are these stagnated green boxes while my project plays back in a choppy fashion.

Any ideas on how to recitfy this issue?

I appreciate any insight!


- Jonathan