My Hi Res 2011 MBP has just started doing something odd - when a user logs out the screen resolution drops. The display properties show that mirroring has been switch on and it thinks there are now 2 displays. The only way to get the resolution / number of screens correct is to restart the machine. Not sure why its suddenly started doing this as things have been fine for the previous couple of weeks since it arrived. Interestingly if I disable "automatic graphics switching" the problem doesnt occur when a user logs out! Can anyone shed any light on the cause of the issue?