I have a test project consisting of 3 forms.  
The first has 3 buttons and 1 ListBox.
The others have 1 ListBox.
All of the ListBoxes are displaying Collections of class
objects using very similar code.  The ListBox on the
opening form and one of the forms opened by a button on
the first form work.  The other produces a GPF when I
requery theListBox after populating the Collection.

I have not been able to find any reference to this problem,
has anyone else seen it?

Is the project fatally corrupted after the GPF?

' *********************************** Form1 Code

Private List As Collection

Private Sub Command0_Click()
    Form_Form2.edit
End Sub

Private Sub Command1_Click()
    Form_Form3.edit
End Sub

Private Sub Command2_Click()
    Dim thing As BillDef
    Dim key As String

    Set List = New Collection

    Set thing = New BillDef
    thing.Id = 1
    thing.Name = "Foo"
    thing.Amount = 10.23
    key = thing.Id
    List.Add thing, key

    Set thing = New BillDef
    thing.Id = 2
    thing.Name = "Bar"
    thing.Amount = 30.2
    key = thing.Id
    List.Add thing, key

    Me.List3.Requery
End Sub

Function source _
( _
    fld As Control, _
    Id As Variant, _
    row As Variant, _
    col As Variant, _
    code As Variant _
) As Variant
    Dim ReturnVal As Variant
    ReturnVal = Null

    Select Case code
        Case acLBInitialize                ' Initialize.
            If IsNull(billList) Then
                ReturnVal = False
            Else
                ReturnVal = True
            End If

        Case acLBOpen                        ' Open.
            ' Generate unique ID for control.
            ReturnVal = Timer

        Case acLBGetRowCount            ' Get number of
rows.
            If Not List Is Nothing Then
                ReturnVal = List.Count + 1
            Else
                ReturnVal = 1
            End If

        Case acLBGetColumnCount    ' Get number of columns.
            ReturnVal = 3

        Case acLBGetColumnWidth    ' Column width.
            If col = 0 Then
                ReturnVal = 0
            Else
            ' -1 forces use of default width.
                ReturnVal = -1
            End If

        Case acLBGetValue                    ' Get data.

            If Not List Is Nothing Then
                If row >= List.Count Then
                    ReturnVal = totalRow(List, col)
                Else
                    ReturnVal = body(List, row, col)
                End If
            Else
                ReturnVal = totalRow(List, col)
            End If
        Case acLBEnd                        ' End.
    End Select

    source = ReturnVal
End Function

'  ****************************** Form2 Code
Option Compare Database

Private List As Collection

Public Sub edit()
    Dim thing As BillDef
    Dim key As String

    Set List = New Collection

    Set thing = New BillDef
    thing.Id = 1
    thing.Name = "Foo"
    thing.Amount = 10.23
    key = thing.Id
    List.Add thing, key

    Set thing = New BillDef
    thing.Id = 2
    thing.Name = "Bar"
    thing.Amount = 30.2
    key = thing.Id
    List.Add thing, key

    Form_Form1.Visible = False
    Me.List0.Requery
    Me.Visible = True
End Sub

Function billsSource _
( _
    fld As Control, _
    Id As Variant, _
    row As Variant, _
    col As Variant, _
    code As Variant _
) As Variant
    Dim ReturnVal As Variant
    ReturnVal = Null

    Select Case code
        Case acLBInitialize                ' Initialize.
            If IsNull(billList) Then
                ReturnVal = False
            Else
                ReturnVal = True
            End If

        Case acLBOpen                        ' Open.
            ' Generate unique ID for control.
            ReturnVal = Timer

        Case acLBGetRowCount            ' Get number of
rows.
            If Not List Is Nothing Then
                ReturnVal = List.Count + 1
            Else
                ReturnVal = 1
            End If

        Case acLBGetColumnCount    ' Get number of columns.
            ReturnVal = 3

        Case acLBGetColumnWidth    ' Column width.
            If col = 0 Then
                ReturnVal = 0
            Else
            ' -1 forces use of default width.
                ReturnVal = -1
            End If

        Case acLBGetValue                    ' Get data.
            If Not List Is Nothing Then
                If row >= billList.Count Then
                    ReturnVal = totalRow(List, col)
                Else
                    ReturnVal = body(List, row, col)
                End If
            Else
                ReturnVal = totalRow(List, col)
            End If
        Case acLBEnd                        ' End.
    End Select

    billsSource = ReturnVal
End Function

' ******************************** Form3 Code
Option Compare Database

Private doctorList As Collection

Public Sub edit()
    Dim thing As IndexText
    Dim key As String

    Set doctorList = New Collection

    Set thing = New IndexText
    thing.start 1, "Foo"
    key = thing.index
    doctorList.Add thing, key

    Set thing = New IndexText
    thing.start 2, "Bar"
    key = thing.index
    doctorList.Add thing, key

    List0.Requery
    Form_Form1.Visible = False
    Me.Visible = True
End Sub

Function doctorsSource _
( _
    fld As Control, _
    Id As Variant, _
    row As Variant, _
    col As Variant, _
    code As Variant _
) As Variant
    Dim ReturnVal As Variant
    ReturnVal = Null

    Select Case code
        Case acLBInitialize                ' Initialize.
            If doctorList Is Nothing Then
                ReturnVal = False
            ElseIf doctorList.Count = 0 Then
                ReturnVal = False
            Else
                ReturnVal = True
            End If

        Case acLBOpen                        ' Open.
            ' Generate unique ID for control.
            ReturnVal = Timer

        Case acLBGetRowCount            ' Get number of
rows.
            ReturnVal = doctorList.Count

        Case acLBGetColumnCount    ' Get number of columns.
            ReturnVal = 2

        Case acLBGetColumnWidth    ' Column width.
            If col = 0 Then
                ReturnVal = 0
            Else
            ' -1 forces use of default width.
                ReturnVal = -1
            End If

        Case acLBGetValue                    ' Get data.
            Dim value As IndexText

            Set value = doctorList.Item(row + 1)

            Select Case col
                Case 0
                    ReturnVal = value.index
                Case 1
                    ReturnVal = value.text
            End Select

        Case acLBEnd                        ' End.
    End Select

    doctorsSource = ReturnVal
End Function

'***************************************** Module1 Code

Option Compare Database

Public Function body(List As Collection, row As Variant,
col As Variant) As Variant
    Dim theRow As Integer
    Dim data As BillDef

    Set data = List.Item(row + 1)

    Select Case col
        Case 0
            body = data.Id
        Case 1
            body = data.Name
        Case 2
            body = data.Amount
    End Select
End Function

Public Function totalRow(List As Collection, col As
Variant) As Variant
    Select Case col
        Case 0
            totalRow = 0
        Case 1
            totalRow = "Total"
        Case 2
            totalRow = totalBill(List)
    End Select
End Function

Public Function totalBill(List As Collection) As Currency
    Dim def As BillDef
    Dim result As Currency

    result = 0

    If Not List Is Nothing Then
        For Each def In List
            result = result + def.Amount
        Next
    End If

    totalBill = result
End Function

' **************************** Class BillDef Code

Option Compare Database
Option Explicit

Public Id As Integer
Public Name As String
Public Amount As Currency

' ********************************  Class IndexText Code

Option Compare Database
Option Explicit

Private indexVal As Integer
Private textVal As String

Public Sub start(indexArg As Integer, textArg As String)
    indexVal = indexArg
    textVal = textArg
End Sub

Public Property Get index() As Integer
    index = indexVal
End Property

Public Property Get text() As String
    text = textVal
End Property

Public Property Let text(value As String)
    textVal = value
End Property