I'm having a similar issue. The calendar works fine in IE8 if the default date value from the MySQL database is stored as text but if the structure in the database is a "date" type then there is an issue/error with the calendar. I've been trying to fix this as well for the past few days. It works perfectly in firefox and chrome.
I fixed it. On the mysql query I changed the format of the date. New query began "SELECT *, DATE_FORMAT(event_date, '%%M %%e, %%Y') as show_event_date FROM...". From there I set the default value of the calendar to the show_event_date value. This is now working in Firefox, IE8, Chrome, etc.