On the event page (Front-end), the Start time is incorrect on the "When:" line. It shows two hours later time (so often shows a Start Time later than the End Time).
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On the Edit Event page (Admin), whilst setting the End Time, the duration shown in brackets is often incorrect with 1:00 hr error.
I am not sure if this is a plugin or browser issue (IE9) but every time I use the calendar control, I get a:
"Are you sure you want to leave this page?" pop-up.
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A few problems but overall, it looks great.