Overnight I usually dim my display till the backlight goes off and leave my computer running. This has generally worked fine in the past. Once a few months ago when I brightened the display the OS had crashed and needed a restart but I didn't stress too much about that - bugs happen in systems from time to time and I guessed it was just a one off since it never happened again. This morning though when I brightened the display the screen went haywire. I've searched through these forums and seen other posts on display problems but most of them seemed to be either on startup or on waking and this was just during normal running with the screen dimmed - the computer was not asleep. The system had seemingly not "crashed" in that the colours on the screen moved and flashed when I moved the mouse and pressed keys. 2 pics are attached... I am fairly paranoid. This machine is my 2nd MBP - the first was replaced by apple after I had 3 repairs within the first 5 months after I purchased the computer. Each repair meant being without my computer for over 3 weeks. Then this replacement machine's screen backlight died about 2 months after I got it and that was repaired - that took over a month. I would appreciate some feedback - has anyone seen this kind of screen behavior before? And do you have any informed opinion whether it is likely a one off bug I should just forget about or if it is a more serious fault whether it is likely related to software or hardware? Thanks to those who take the time to respond!!