1. That did not directly answer either of my last two questions.
2. Does that mean
- they contain values (lists) that will be used in Data Validation cells
elsewhere, or
- the values in them will be populated by choosing values from a DV drop-down list?
3. Does "other columns" mean A:E?
4. And is this column (6th) a formula? If so, then the existing Worksheet_Calculate code, adjusted to column F should do the job, apart from a modification that will be needed because the sheet will be protected.
5. Repeating myself I know but confirm this means in columns A:D? If not, where?
6. If you are going to make them unselectable and/or unchangeable the code is also going to have to lock them as they become "Yes". Is that OK?
7. Are we dealing with rows 2:51? If not, more info please.
Please try to address each point carefully.