First Person Prefab Stopping?

I'm using the first person prefab in the world I made. It will move around for a few seconds then slows to a crawl and eventually stops. I'm pretty sure he's not running into anything because it just goes through walls and retracing my steps doesn't work either. Ideas?

For anyone interested, I didn't give the character controller connected to my world a big enough radius. The result? The character stopped as soon as it hit the boundary.