Second Life has a feature that prevents you from accidentally running two copies of the program at the same time. If you try, it lets you know that Second Life is still running, and to check the tray for a minimized version of the program.
Problem is, the code for this is just checking for ANY program window entitled "Second Life." Go ahead; make a folder called Second Life, and open it up so the window's title bar reads "Second Life". Then try to run Second Life. It doesn't work.
This is definately a class C bug, but it's an interesting quirk. I noticed it because I have all my SL stuff in a folder on my desktop called "Second Life", and when I have that window open, I can't run SL itself. ^_^