i just got a new external monitor (22" wide) and i have my macbook pro running in clamshell mode. But every once in a while my desktop will chagne randomly. I have checked to make sure that hte "change desktop every:____" is off and it is. I chagned my desktop when i turned my external monitor on but i am confused on why it is still changing? I have the monitor and the mbp's screen mirrored so it is not extended or anything. Any suggestions on how to fix it?