The file wants do an upgrade to 4.25. I already have that version installed. I also can not log in to the upgrade. I haven't set up anything yet for the mt.cgi file yet..
Don't have a clue as to what it's supose to do.
edited version
Reported on Movable Type 4.2
Is this a completely new install? If so, have you tried deleting mt-config.cgi and re-running mt.cgi?
What happens when you run mt-check.cgi?