Janson --
No, I do not believe this is possible. Those fields are open and editable
and I know of no way to lock them. Think about what you are asking,
however. Why are your team members changing these dates? Are they trying
to tell their PM's the date they actually started and the date they actually
finished? If so, perhaps you should modify the default My Tasks view to
include the Actual Start and Actual Finish fields so that people can enter
this information. Or are they trying to tell their PM's that they KNOW they
will start late or finish late? If so, this information is valuable and
should not be forbidden. Otherwise, you must make this a training and
performance issue with your team members. Hope this helps.