Ummm, is there not a bug fix for this? This is obviously incorrect to have submissions close on 00:00 on the deadline date. People expect to be able to submit up until 23:59 on that day. I have just had this bite me for one conference and I've only got a few hours until the same thing happens with a 2nd conference.
I just went in and changed the date directly in the database. That is, submissionsCloseDate was set to 2008-3-31 00:00:00 and I changed it to 2008-3-31 23:59:59. With the 1st conference, the organizers realized there was a problem and changed submissionsCloseDate to a later date in order to keep abstract submissions open for the remainder of the day. Unfortunately, they didn't notice that they also had to change regPresenterCloseDate and this caused problems for quite a few people. It sounds like this might be what happened with Elena's site as well.
Of course, this still needs to be addressed so that, when the date is changed via the admin system, it will be set to close a the END of the day.
Web Development for the Academic Community
Hamilton, ON, Canada