vb.net - 理由もなく System.IO.FileLoadException がスローされる

Question

When switching between tabs, whenever I enter the tabCurves control at any point after the initial entry, a System.IO.FileLoadException is thrown at the line lstCurves_SelectedIndexChanged(Nothing, EventArgs.Empty). This is completely baffling to me, as I have another sub (tabNURBS_Enter(...)) that has nearly identical code, but does not throw any exceptions.

What is going on here?

Code:

Private Sub tabCurves_Enter(ByVal sender As Object, ByVal e As System.EventArgs) Handles tabCurves.Enter
    ' See if the tab enter event is marked to be supressed...
    If tabMain.Tag Is tabMain Then _
        Exit Sub

    With lstCurves.Items
        ' Remove old entries.
        .Clear()

        ' Add new curves.
        For I As Integer = 0 To m_NIS.Curves.Count - 1
            .Add(m_NIS.Curves(I).Name)
        Next I
    End With

    ' Update selection.
    lstCurves_SelectedIndexChanged(Nothing, EventArgs.Empty)
End Sub

Private Sub lstCurves_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles lstCurves.SelectedIndexChanged
    If lstCurves.SelectedIndex = -1 Then
        ' Since no curve is selected, disable all UI controls except the add button.
        ' ### code snipped ###

        ' Reset fields.
        ' ### code snipped ###
    Else
        ' Since a curve is selected, enable all UI controls.
        ' ### code snipped ###

        ' Update the fields.
        ' ### code snipped ###

        ' Force update of slider.
        sldCURVKeyframes_ValueChanged(Nothing, EventArgs.Empty)
    End If
End Sub

Private Sub sldCURVKeyframes_ValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles sldCURVKeyframes.ValueChanged
    ' Enable\Disable controls depending upon whether the slider is enabled or not.
    ' ### code snipped ###
End Sub

Private Sub tabNURBS_Enter(ByVal sender As Object, ByVal e As System.EventArgs) Handles tabNURBS.Enter
    ' See if the tab enter event is marked to be supressed...
    If tabMain.Tag Is tabMain Then _
        Exit Sub

    With lstNURBS.Items
        ' Remove old entries.
        .Clear()

        ' Add new curves.
        For I As Integer = 0 To m_NIS.BSplines.Count - 1
            .Add(m_NIS.BSplines(I).Name)
        Next I
    End With

    ' Update selection.
    lstNURBS_SelectedIndexChanged(Nothing, EventArgs.Empty)
End Sub

Private Sub lstNURBS_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstNURBS.SelectedIndexChanged
    If lstNURBS.SelectedIndex = -1 Then
        ' Since no curve is selected, disable all UI controls except the add button.
        ' ### code snipped ###

        ' Reset fields.
        ' ### code snipped ###
    Else
        ' Since a curve is selected, enable all UI controls.
        ' ### code snipped ###

        ' Update the fields.
        ' ### code snipped ###

        ' Force update of sliders.
        sldNURBSCtlPoints_ValueChanged(Nothing, EventArgs.Empty)
        sldNURBSKnots_ValueChanged(Nothing, EventArgs.Empty)
    End If
End Sub

Private Sub sldNURBSCtlPoints_ValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles sldNURBSCtlPoints.ValueChanged
    ' Enable\Disable controls depending upon whether the slider is enabled or not.
    ' ### code snipped ###

    ' Update fields.
    ' ### code snipped ###
End Sub

Private Sub sldNURBSKnots_ValueChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles sldNURBSKnots.ValueChanged
    ' Enable\Disable controls depending upon whether the slider is enabled or not.
    ' ### code snipped ###

    ' Update fields.
    ' ### code snipped ###
End Sub

---

Based on Adrian's comment below, I decided to go snooping in lstCurves_SelectedIndexChanged and commented out all the code and slowing uncommented each line until I found the problem (in bold below).

Private Sub lstCurves_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles lstCurves.SelectedIndexChanged
    If lstCurves.SelectedIndex = -1 Then
        ' Since no curve is selected, disable all UI controls except the add button.
        btnCURVRemove.Enabled = False
        btnCURVRename.Enabled = False

        ' Reset fields.
        txtCURVPreInfinity.Text = ""
        txtCURVPostInfinity.Text = ""

        sldCURVKeyframes.Enabled = False
        sldCURVKeyframes.Value = 0
        sldCURVKeyframes.Maximum = 0
    Else
        ' Since a curve is selected, enable all UI controls.
        btnCURVRemove.Enabled = True
        btnCURVRename.Enabled = True

        ' Update the fields.
        With m_NIS.Curves(lstCurves.SelectedIndex)
            txtCURVPreInfinity.Text = .PreInfinity
            txtCURVPostInfinity.Text = .PostInfinity
            sldCURVKeyframes.Enabled = True
            sldCURVKeyframes.Maximum = .Keyframes.Count - 1
            sldCURVKeyframes.Value = 0
        End With

        ' Force update of slider.
        sldCURVKeyframes_ValueChanged(Nothing, EventArgs.Empty)
    End If
End Sub

Keyframes is of type IList(Of Keyframe) which is actually a property that returns a cast of an internal list of type EventList(Of T) Implements IList(Of T) to type IList(Of Keyframe). EventList(Of T) is a wrapper that throws events when an item is added, inserted, removed, about to be removed, modified, or the list is cleared or about to be cleared.

それが私が経験している問題の原因ですか？

---

m_NIS とアニメーション カーブ オブジェクトを定義する関連ファイルを次に示します。ダウンロード