DateTime returning formatting errors

When using a DateTime field (in this case Authored On, but I've also tested it on a DateTime field that I created), I am unable to submit a value (happens with both Date/Time, and just Date).

The Authored on date is invalid. Please enter a date in the format 13131313-MayMay-1414 12:0505:2626.

The DateTime that I submitted was 14/05/2013 12:15:30 PM

A cursory search shows that datetime_datetime_validate (core/modules/datetime/datetime.module:648) is looking at $input['object'], which isn't being properly retrieved from the form. I had traced it farther this morning, but work has gotten in the way.