DBCombo Box - Urgent Help

Hi All,
I am using VB6 Pro SP3 and just upgraded to SP4.
I have an application on a clients computer and users Access 97 on the Server.
The program has been running fine for approx. 2yrs until now.
I have a DBCombo which is populated from a Table in the Database and when the user makes a selection , that selection is stored in another table ( the main records ).
My Problem.
Out of the 25 selections only 16 that are selected will save in the main record table.
5 give error 524 - not allowed zero length string and the other four show a blank field in the combo.
Does anyone know what could be wrong ?
As my computer has two hard disks , I loaded the application to my main disk and the database to the other to simulate a network and all is fine !!!!
Please help.
Regards,
Trevor

Your statement does not make sense.
How can a system works fine have problem?

If you really have problem, this is the size of the fields in the table. When the user enters a value that is larger than the size of the field, the value is rejected by the database mechanism. So the value of the field then is Null. When a Null value is saved in a field that does not allow Null, the database mechanism generates the error you described.

In order to avoid (not solve) the problem, allow the field to accept Null value, or enlarge the size of the field.
In Visual Basic interface, truncate the input value to fit the size of the field prior to the edit or update or addnew command.

AnhMy_Tran