Impossible to create event without reminder now?

Hi,

	I think I have just found a bug in Lightning about event and reminder 
but I can't find any related report in bugzilla.  Here is the step to 
reproduce:

1. Create a new event:
    * Whether it is All day event does not matter.
    * Any Start and End time

2. Make sure that Reminder is set to "No reminder"

3. Save the event

4. Check the event again and Reminder is set back to 30 minutes.

	I've tried several methods to get rid of the reminder but without any 
success.  This is a bug for me.

	I'm using:
Thunderbird 24.2.0
Lightning   2.6.4