Neight fom GUI nor VBA.

searched google groups found semi-solution:
<<
Type the number 1 in any empty cell (make sure that the
NumberFormat of the
cell with the number 1 is General or Number)
Copy it
Select all problematic date cells
Paste Special = Operation | Multiply


It worked. Question is why and how to fix it.
The cell formula contains RTD function.

Thank you.