I seem to be having a problem whereby my machine wont shut down completely. It goes through the shutdown process; the monitor, keyboard, and mouse all shut down but the CPU itself stays on. at that point, I have to yank the plug to turn it off because it wont accept input from any other button or control. It cant be turned off manually any other way and no other button will turn it back on fully.
This is a problem that has manifested after installing Ubuntu.