For some weird reason when I'm playing my map, my game keeps automatically sending me to prone at random times. I have already checked my keyboard mapping, but I haven't changed it, and everything is normal. Also, It happens randomly, I don't have be doing anything for it to occur.

Here is an example:
http://youtu.be/YIrpiaw4dv8

I've tested other maps and this doesn't happen. Any help would be appreciated. Thanks!