Message box for cell change

[Prometheus]

I have a fairly large spreadsheet in which I have protected certai
cells from being accidentially modified by the user by setting Data -
Validation -> Custom -> =. I have found that it would be much mor
beneficial if I could instead have a pop-up box when a user tried t
modify a certain cell asking for verification before allowing them t
modify the cell. Is there a way to specify certain cells to call
pop-up box when a user tries to modify them

 

[Prometheus]

Delayed reply, been busy lately

Actually, if you could post a few lines of sample code that would be
great, I've never worked with the worksheet selection change event.

Thanks.