It looks like the web service xml serialization of the datetime datatype
adds a time zone indication on to its text representation. Info path doesn't
interpret this properly. If you handle the OnAfterChange event for each
datetime field and strip off the timezone, InfoPath does the right thing.

           public void startDate_OnAfterChange(DataDOMEvent e)

           {

                 // Write your code here. Warning: ensure that the
constraint you are enforcing is

                 // compatible with the default value you set for this XML
node.

                 if (e.Site.text.Length == 33)

                       e.Site.text = e.Site.text.Substring(0,19);

           }