In accounts and privileges you can restrict access to fields by adding a calculation.
For example give permission to edit only when: isempty( checkboxField )
Thanks Jens, that is indeed the way to go!
So... I have a variation on this question. I've got the "locking" records thing figured out in terms of making a record non-modifiable by way of a permissions set based on a calculation (TABLE::FIELD = "LOCKED"), but how would I set a record so that the content of the fields in that record is not VISIBLE? i.e. the user could see that there is a record THERE on a Report layout, but not be able to see what the information is in the fields if they view that individual record in another layout.
The only way I can think of is to have any layouts with sensitive client information become inaccessible by calculation (TABLE::FIELD = "LOCKED") but I'm not sure how I go about that.