Recently upgraded my 27" iMac (mid 2011 model) to OS X Lion 10.7.1 (11826). Since upgrading I have experienced significant screen redraw problems when scrolling in List Mode--the image literally breaks-up and pixelates. I saw a thread on the Apple support site at (https://discussions.apple.com/thread/3257215?start=0&tstart=0) dating back to mid-September, but have not seen any follow-up. Have others seen this problem and/or resolved it? It appears that Apple is not acknowledging this issue, nor aiding in its resolution.