How do I lock any field in a form after data entry

[zwave]

I would like to lock a field after data has been entered to prevent users from changing the data. I would also like to include a message box that asks users whether the information entered is correct. How do I go about this?

PS: New to Access, first real DB attempt, detailed information will be appreciated

[RuralGuy]

You do not trust your users?

[ajetrumpet]

You do not trust your users?

I enjoyed a good laugh today. Thanks Allan!

[zwave]

It's a medical research database, and this will only apply to certain fields such as Date of birth, Medical record #, processID etc assigned to each study participant.

[RuralGuy]

You can use the Current Event of your form to "lock" any control you choose that already contains a value.