I have used data validation to set parameters for valid data entry and I have
also used cell protection to prevent any type of data entry. What I am trying
to do in this instance is to prevent data entry but, instead of the standard
message that pops up when using cell protection, I want to display a
customized message such as:

Data for these fields must be entered in "Project Assumptions"

Can Data validation be used to prevent data entry of any kind or do I need
to look for a VBA solution?