Hi boys and girls. I have a cinema display connected through a mini display port to dvi connection. After connecting and immediately loving all the new real estate, I find I can't scrub through the timeline decent at all. It's super slow and really choppy and unpredictable even with a 2 minute clip. When I playback, it works pretty well but the canvas goes black. I get the same result with my iMac and my MBP. Is this a memory issue?