End Date: If It Occurs before the Start Date, Values Are Zeroed Out and Event Does Not Show Up in Calendar

When adding/editing an event, if the date and time set in the "End date" fieldset would occur before the date and time set in the "Start date" fieldset, the "End date" values are all reset to zero and the event doesn't show up in the calendar. To fix this, the user must edit the event and set the date and time in the "End date" fieldset to come after the date and time set in the "Start date" fieldset.

When viewing/editing the event, it may show a value equivalent to zero in some places. For example, the time may be displayed as "12:00 AM" if using the 12-hour notation (which is the same as "0000" in the 24-hour notation). When editing the event, if a value equivalent to zero isn't available, the lowest non-zero value will be used in its place (and may still show a zero value for that field when viewing that page). For example, if a select box is used for the month, it would default to "January", even if the value for the month when viewing the event shows up as zero.

Would there be a way to prevent the user from submitting an event (or changes to it), as well as showing them an error message regarding this, until they fix the date and time in the "End date" fieldset?