Hey, I know this about a year too late, but for anyone looking up this section of code, here is a solution for you:

Private Sub WMPWindow_PlayStateChange(ByVal sender As Object, ByVal e As AxWMPLib._WMPOCXEvents_PlayStateChangeEvent) Handles WMPwindow.PlayStateChange  

        Static Dim PlayMe As Boolean = True
        Select Case WMPwindow.playState
            Case 10
                If PlayMe Then
                    WMPwindow.Ctlcontrols.play()
                End If
            Case 8
                If SongsListBox.SelectedIndex = SongsListBox.Items.Count - 1 Then
                    PlayMe = False
                Else

                    SongsListBox.SelectedIndex = SongsListBox.SelectedIndex + 1
                    PlayMe = False
                    WMPwindow.URL = "C:\Users\SamLemx\Desktop\Music\" & SongsListBox.SelectedItem.ToString 
                    WMPwindow.Ctlcontrols.play()
                    PlayMe = True
                End If
        End Select
   End Sub 

This will handle the PlayStateChanges that happen, and there are a few between each song (7!). I'm sorry this probably doesn't help the original requestor, but hopefully it's useful to someone in the future!!

I know this is a tricky one, I've had three developers on my team look at this with me, and the Google Admin isn't bringing up any references to this, so any help that I could get would be appreciated.

PreRender works!! Thank you so much for helping me on this topic. I told my boss that I was going to give up on this and just validate all the checkboxes upon submit, but you saved that application! I suppose I owe you a portion of my paycheck now?

I tried using the RowDataBound event and I get the same results. You mentioned using the PreRender event, which I have never used. I looked it up on MSDN, but not sure how or where to implement that event. Any help on that method?

You declare a mas_list(), but on your code I don't see any Class for mas_list, so that may be the problem, that it doesn't exist.