I started searching the threads to see if others had the following issue: Mid 2009 MBP 2.8 5,3 Connected to HP Compaq LA2205WG Monitor via MiniDisplayport to Displayport High Performance Mode Native Monitor 1440x900 External Monitor 1680x1050 Problem Intermittent external monitor flicker Interval varied from every couple of minutes to several a second X Factor - I use an Apple bluetooth keyboard and magic pad when using the external monitor described above Also note- The flicker only occurred when connected to the monitor above - use external display on other occasions at different sites with no issue. So, I tried to trouble shoot. Checked connections etc. All seemed ok. Noticed that the display was fine as long as I was not actively moving the curser on the display. Thought maybe it was a certain application. Could not find a pattern. Finally shut off bluetooth (read something that made me think this may be a factor?) It seemed to stop flickering. Decided to try and see if a bluetooth setting would change the issue. I unchecked discoverable in the advanced bluetooth settings, and have not had the flicker for several hours? I am using the bluetooth mouse and keyboard without any issue now. Thought it was interesting, so decided to post.