I can't think of anything, and there are some ultra geeks who "fold" and would highlight the dangers if they were there. If you aren't overclocking your computer and it's clean, there is no reason that your cpu should overheat. And it uses the harddrive so little it's not worth any concern. In a strange sense if you run F@H on your computer 24/7 it will be healthier than turning it on and off.
Thank you.