Can't use custom profile fields.

[Reeve of shinra]

Try changing field required to "no" and see if you can go in and edit it then.

edit1: If that doesn't work, try reverting those manual file edits to see if they are the cause. (looking at the code, I personally can't tell)

edit2: The vehicle mod seems to make use of vbulletins profile fields.... so even if you remove the hack, if the profile fields for the vehicles are still in place, vbulletins default code will still pull the info in them and display it. (if that made any sense)