At the end of Jeffrey Richter's talk yesterday he showed the depth to which Microsoft has gone to ensure that Windows runs all applications well.  He an exe file called armymen.exe (here's another mention of it) that was actually just a renamed copy of Notepad.exe.  It had three subfolders, each with a zero byte file in it.  When he clicked on it, Windows XP resized the screen to 640 x 480 at 16 colours and disabled that ALT + Tab task switching.  Closing the task returned the screen to normal. 

Under the covers, Windows has some hard-coded logic that checks for the name 'armymen' and the related directories and files and adjusts the screen accordingly.

This highlights the lengths that Microsoft have gone to in order that all applications continue to run.  It also makes me glad that I'm not writing operating systems.