For some reason if you are having boot issues running Fedora 16 on the old AMD 939 4400+ platform combined with an ASUS A8NE motherboard, I had to modify my grub bootloader defaults to the following:

This stopped various in OS crashes that left me without any error messages, and an issue with modprobe not responding (hanging in an eternal loop). My system is overclocked to 2.5 Ghz, Hyper Transport multiplier set to 3x instead of 5x and Cool n' Quiet is turned off.

Hope this helps!