Eric, I also booted into safe mode yesterday and so far so good, no white screen. Thank you for this suggestion. I am optimistic that this will take care of the problems. I also had the System Preference and iPhoto issues and they seem to be fine now. HPR3 and Eric, thank you for the postings! I very much appreciate the support!
I've got a weirdo issue, too. The 10.8.3 update killed most of the items in my menu bar - can't see the volume setting or date & time. When I pull up System Prefs from the Apple shaped menu header it takes about two full minutes to come up. Then, when I click the button to make it show date/time in the dock, I get pinwheel for about a minute and a half, then the Prefs screen crashes. I can't make it show the date and time no matter what I do. The same thing happens when I check the 'show volume in menu bar' box.
This stinks - the update fixed a weird graphics problem I was having in Safari - but I am not happy I can't show the time or volume, since I use those displays a lot.
I'm also having trouble pulling the Preferences window back up if I minimize it. Trying to open it or clicking anything is yielding lots of pinwheel, frozen screen, and crashing.
I'm experiencing severe graphical glitches since upgrading to 10.8.3. I've reset both the PVRAM and NRAM, neither of which made a difference. I've re-installed the OS, which did not fix it. I cannot boot into safe mode, as the boot progress bar will get permanently stuck about 1/4 of the way through.
Here are three videos I've taken recently of the problem happening: