>am using Service Pack 4
>
>I have found the problem to happen only when I load new unit forms. Here is the sample code I used to test it.
>

>Dim UnitForm() as new frmUnit
>Dim UnitNumber as long
>
>Private Sub MDIForm_Click()
>' Program unloaded fine before I clicked to make a new unit form
>' It will give an illegal operation now
>
>' Add a new form to our form array
>UnitNumber = UnitNumber + 1
>ReDim Preserve UnitForms(0UnitNumber) As New frmUnit
>
>UnitForms(UnitNumber).Show
>End Sub
>

What is th "0" on this line:

ReDim Preserve UnitForms(<B>0</B>UnitNumber) As New frmUnit

Do you have "Option Explicit"? It is the kind of the thing that is trap with this statement!