When I boot my iMac (latest model to date, baseline 27"), it loads up properly for a while, and then before the desktop appears, I get this really messed-up screen. The photo is attached below (and links to imageshack). However, after showing that screen for a few seconds, I get the desktop, and I don't have any issues during my day-to-day activities. Has anyone had such an experience to date? It's annoying and maybe a tad bit worrying, but as I can still get mission-critical stuff done and out of the way, it's not all the way up there in my priority fix list.