I have created a RTD server in .NET which gets information from a
database via a web service. While the cells are updating like when I
copy a range it seems to take a while for the whole group to update.
While that is happeing I cannot do anything with Excel. I would like:

1) to put a place holder in the cell indicating it is being updated
(example: #updating) so the users would know what's going on and be
able to work in other parts of the sheet but which would seem like an
error to dependant cells so they don't make calls to the web service.

2) rtd to call back the cell and replace the #updating value with the
real value when it changes.

Does anybody know how to do either of these things?