I just noticed on my Mac running Maverick when I click on the Main Drive I get a little pencil with a slash through it
in the lower left hand corner. If I click on any of the other folders I do not get this.
Actually, you’re not in the main drive, although I see why you think you are. You’re actually in one level above the main drive, the computer itself. What you’re seeing is a list of drives. The pencil with the line through it means you have no write access, which makes much more sense in a read-only folder than here.
Mountain Lion appears to be the name of your actual main drive.
Okay, I think I understand how it works and it looks normal. For a sec I actually though I had a virus
which I never got on my Mac. Windows is a different story