I'm wondering if it's possible to lock an ActiveX textbox from text entry or even being clicked on unless another cell indicates that it actually requires input from a user?

More detail: right now, I have a sheet where, based on a drop down field, the cell to the left of a textbox populates a label and the color of a cell underneath the textbox changes to green if said textbox needs input from a user.
Even more detail: the spreadsheet...