External Display Won't stay asleep: stuck in sleep / wake loop I have a mid-2012 MacBook Pro (running Mountain Lion) connected to an HP Pavilion 23xi external display. The external is connected via DVI-->Thunderbolt adapter, is set as the primary display and the MacBook Pro is mostly in Clamshell mode.

When I put the Mac to sleep, the displays sleep as they should. However, if I put just the displays to sleep (ctrl - shift -eject or hot corner) the internal display behaves as it should but the external display goes to sleep for a second or so then immediately wakes up. It then gets caught in a sleep / wake loop.

The problem is similar to the one described in this question but, in my case, resetting the SMC hasn't helped. Wake for network access is off and the problem persists when the display is the only peripheral connected to the mac.

This is what the Console shows when this happens:


Any idea how to solve this?
I am having the same problem with this HP monitor connected to a Mac Pro.  My only solution was to connect via HDMI cable instead of the Thunderbolt/DVI cable.  That works.