Windows seems to have a limit of how many windows it can have open at once-- and IE seems to be the worst culprit. When the limit is exceeded (e.g. 60 IE windows open at once), I get really odd behavior like a gray blinking screen with random chunks of the IE user interface showing up in random spots on the screen. Once I close a few IE windows (with Alt+F4 since I wouldn't know where to click with the mouse) the problem goes away.
This is Windows Server 2008 and IE8, if it matters, but I've seen the same behavior on all Windows OS's since XP and all recent versions of IE. I have 4GB RAM and a big swapfile, and task manager doesn't even show me using 3GB, so I'm running out of memory overall-- instead there's a special kind of windows resource that I'm exhausting.
I remember reading years ago (in an aticle I can no longer find) that there was a registry setting that you could increase the limit of windows (or just IE?) to allow more windows to be open before Windows barfs.
Yes, I realize an easy fix is to close all 60 IE windows, but often I'm in the middle of researching something and don't want to deal with the hassle of re-opening 10 of those windows that I really need.