This concerns all beta versions of 4.0, even including tonight's CVS HEAD, which is supposed to be Beta-4.
Whenever I use an unmatched <p>, or even a <p/>, without an explicit </p> in a page with a DatePicker, I get a really strange error from MSIE, in that MSIE pops up the error dialog "Operation aborted." It does NOT happen when I match the <p> tag with a </p> or use other components, such as TextField.
The simplest page yielding this problem:
<input jwcid="@DatePicker" value="ognl:theDate" type="text" size="12" />
Just remove the <p/> and it works. Very absurd. Have tried with a handful of MSIE 6 machines.