I recently upgraded to CS4 and this issue appeared, so far only in Flash: a few times every minute, the screen blinks and floating panes that are not "attached" to the window will do a redraw of some portion of the pane (usually the top) as seen in the images below. It has a have a preference of redrawing portions of the timeline in the actions pane, however this is not always the case. The only solution is to close the pane and open it again, or minimize Flash. It's difficult to pinpoint what triggers this; sometimes doublelcicking into a movieclip will make it happen, sometimes advancing the timeline, sometimes switching to another program. I am on a Windows XP Pro SP3, Intel 2.4 Quad Core, 3.5 GB RAM, NVIDIA Quadro FX 3450/4000 SDI video card with all drivers updated.