Fixed - went into the settings via web interface - unlocked the change restrictions, and then used the settings map to fumble my way through going from Chinese back to English.
Guess there was a hack...
Came into work today and found our networked printer had printed 75 pages of gibberish, and the printer menu all in Korean, with seveal "lock" icons that seem to prevent changes.
Suggestions? First thing I would like to do is return to English!