Had a project magically switch over to the playback issue this morning. Not sure if i’m just stupid it what, but after looking at every solution i’ve read in this thread so far with no success – I noticed an option within the playback settings (right click on your source and click on playback settings) labeled “Desktop Video Display During Playback” mine was unchecked. After I checked it, playback was back to working perfectly with no issues. Now the option’s grayed out.
Maybe worth looking at if there’s someone out there who hasn’t tried that yet.
Mac OS X 10.7.5
CS5.5