ajax extension works in chrome and firefox but not IE

see code box for the extender in question. It seems really strange that a a MS product like ajax does not work with their own browser? Is there some kind of patch/override/etc like with CSS to account for browser differences

<ajax:calendarExtender ID="calExt" runat="server" TargetControlID="someDateBox" Format="MM/dd/yyyy" ></ajax:calendarExtender>