GIMP: Random Freezing / High CPU Usage

I can use the gimp portable edition fine for a short period of time but after about 30 minutes of working in it, it seems to freeze up (all gimp windows and documents). It doesn't give me the opportunity to save at this point and I end up loosing 30 minutes of work. It's happened 3 times in the past 2 days. (1.5 hrs work lost).

Does anyone have any ideas how I should start troubleshooting?

Here's a screenshot:

http://s179269986.onlinehome.us/gimp-freezing.JPG