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