I am experiencing the same issue, only the error seems to differ based on the server it is running on.  I have a development server which works correctly, but the production server generates the error above (Object doesn't support this property or method; line 1163).  Both servers are windows 2000 server running IIS 5.0.

 Also, removing the default date does allow the popup control to function initially, but if I try to select another date after a postback has completed on the page, the error is generated again.  So the error is presumably caused by the text being present in the input box anytime the page is loader.

 Any help would be greatly appreciated...