How do I find a process I know I must have running that I can't see? How do I get rid of a process I don't want?

To find a runaway process, use the ps command. On linux machines type ps -augx. The man pages (man ps) show all possible flags.

To kill a process once you've found its process ID (PID), type "kill PID". If that doesn't work, you can use "kill -9 PID". If you need to kill all your processes, you can use "killall -u 'login name'"