Is there any solution yet to this issue?  I just did a completely clean install of the latest version (5.1.4 Community Edition) on a Windows 2003 R2 server with standalone SQL Server 2005 and am having exactly this issue.  I have not seen any solution posted anywhere online.  Please help!

I threw in a try/catch around the offending code:

/admin/containers/visibillity.ascx.vb line 206

Its a half a$$ fix, but works like a champ:

        Private Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs) Handles MyBase.PreRender
            If Not ModuleContent Is Nothing AndAlso Not ModuleControl Is Nothing AndAlso Not IsAdminControl() Then
                Select Case ModuleControl.ModuleContext.Configuration.Visibility
                    Case Entities.Modules.VisibilityState.Maximized, Entities.Modules.VisibilityState.Minimized
                        Try
                            DotNetNuke.UI.Utilities.DNNClientAPI.EnableMinMax(cmdVisibility, ModuleContent, ModuleControl.ModuleContext.ModuleId, ModuleControl.ModuleContext.Configuration.Visibility = Entities.Modules.VisibilityState.Minimized, MinIconLoc, MaxIconLoc, Utilities.DNNClientAPI.MinMaxPersistanceType.Cookie, Me.AnimationFrames)
                        Catch ex As Exception
                            'ignore it
                        End Try

                End Select
            End If

        End Sub