Set Variable [ $counties ; List( student::UserSelectionCheckbox ) ]
If [ ValueCount($counties) > 0]
Enter Find Mode [ no pause ]
Set Variable [ $i ; $i + 1 ]
Set Field [ student::county ; GetValue( $counties ; $i ) ]
Exit Loop If [ $i = ValueCount ( $counties ) ]
Show Custom Dialog [ "Error - you must check a county to perform a find" ]
Mike's method works just fine. You can also set up a relationship that matches your check box field to the records and then Go To Related Records could also be used.
Another observation, if your check box is a global field, you can simplify Mike's example by not using a variable. Just refer to the global field instead of the variable, but only if you've specified global storage for that field.
Mike, you are a life saver. I appreciate your help.