I have a 98 Accord and strangely enough mine freaked out Today (Tues.)
too. I locked it. Later I unlocked it and entered the passenger side
and the alarm went off. Key then wouldn't turn in the driver's door
and I think the remote is going dead/getting weak. The remote wouldn't
cancel the alarm.

ANSWER: When the alarm goes off I believe the procedure is shut the
door and press and HOLD the Lock or Unlock on the keyfob for...I
think...5 seconds. Doesn't always work for me the first time but it
does work. Never heard the radio code thing before. Hope that helps.

kevin