Notepad bug
Paul Domag's blog has an interesting entry about a bug of the Windows' default text editor Notepad.
It seems that creating a file in Notepad and typing in a 4-3-3-5 letter combination then saving and closing the file recreates the bug. Try typing "AAAA BBB CCC DDDDD" (without the quotes) in a new Notepad file, save it, close it, then open it and you'll see squares instead of the letters.
I opened the file using Notepad2 and still the squares were there. Interestingly, I tried opening it with UltraEdit, and viola, the letters were back and the squares gone. Hmmm. It seems it has something to do with how Notepad and Notepad2 (not created by Microsoft BTW) internally interprets the characters upon opening the file.

