They won't uncheck themselves. Something else must be involved.
Are you sure that you are looking at the same record the next time?
Could it be that your field has global storage specified and you are hosting this file over a network? (Changes to the value of a global field, when made by a client of the system, are not retained once the client closes the file.)
Any script trigger set up on the field?
Any auto-enter calculation or looked up value specified in field options for the field?
Yes the same records
No global storage
Yes network but I am the only one accessing it
Yes filed involved in script but only as: if (checkbox = 1; then calculate this and that)
No auto calculation...
Any more ides?
Describe exactly how this happens:
the next time come back on the layout
And are you using FileMaker Pro or FileMaker Advanced?
I identified what was the problem.... it was the regular import on those records. It was scripted as delete and add new records... instead of update the records and add the new ones.