Monitor has a red tint

I just inherited a new-ish iMac from a friend, and the monitor has a red tint. I can still use the computer, but it is really annoying to look at. I'm not sure if this is a setting that he adjusted for some reason, or is something is broken. Is this something I can fix easily? I tried calibrating the colors but it still didn't do anything. Any help would be greatly appreciated.
Thanks,
Charlie

Being how new-ish?

If under warranty a job for Applecare.

You'll probably need a new monitor. My first mac had that problem but green and it drove me insane.

I bought a used screen for a G4 iBook once and it was red. It would boot up a really dark, blood red and fade to a light red tint within a minute or two but it'd never go away completely.
I had to replace the screen. I would assume you'd have to do the same.
But if it's new enough, see if you can get it fixed under warranty.