Ok, so I have a 2010 13" MBP. I usually use it connected to my desktop monitor. First I used it in clamshell mode and now I use it open with my desktop monitor in back. Also more recently (like for a week/week and a half), I have not been turning off my MBP each night. This seems to be where the trouble started (I have no idea why, and apparently a restart doesn't fix it anyways). A few days ago I noticed that if I shut the computer (to put it to sleep), that it would wake up the monitor (Honestly, I think that's how it is supposed to work, but it had been letting me get away with putting it to sleep by closing it). But then I noticed that when I opened it, it didn't always turn on the desktop monitor (which I always have on so it just wakes up when the computer sends it info). It seemed the best way to fix this was to close the computer and open it again (at first putting it to sleep and waking it might work). That worked for a short while. Then that wouldn't turn the desktop monitor on (though it would let me move my windows into it like it was on). But if you went to display options you could still gather windows and it would detect displays. And then I noticed eventually the desktop monitor would eventually turn on randomly. Well, today, it just acts like there is no monitor attached period. You can't move a window into the invisible desktop monitor. Hitting detect displays does nothing and so does hitting gather windows. If you close the MPB, it doesn't turn on the desktop monitor. Try to disconnect the monitor and reconnect does nothing. I'll add that if I disconnect the computer the monitor says "Cable disconnected" (It apparently says this as well when the computer is off as I have another MB that I just tested it and when the MB was off, it would say "Cable disconnected"). But when connected to the MBP, it says "No input signal" (Apparently though if it is connected to the MBP when the MBP is turned off it just says "No input". Only difference between the two is the MBP was plugged in, the MB was not. So I am assuming that it detects electricity coming from the connection to decide if it is getting no input vs. disconnected). Any suggestions?