You can protect cells (unprotect cells) then protect the worksheet
to control where you can go with the TAB key. You can use an event macro to
keep you out of the "next" cell and place you somewhere else.
You can select all cell (ctrl+A) then chose which cells that
you want to unprotect i.e. Edit, GoTo, Special, choose something
to protect or unprotect later based on text/formulas etc.