Don't disable RPC
I consider myself to be computer-savvy, seeing as how I spend a great deal of time using them. However, I had no idea what the RPC protocol (I now know full well whe it is) was and disabled it because my friend thought it would be funny (this was during the incident where nearly everyone with Windows XP was having random shutdowns related to the RPC protocol). RPC controls about half of what windows does, including system restore. Much to my chagrin, I was forced to format and reinstall windows.