I also had this problem right now:
Click on editor,
Then select "Junon Clan Field" map,
Click on the map, you get a warning message (select NEW to create a new spawn), click OK,
Choose "new",
Then when I click on map I got this error 6 (overflow) and it goes on debug on this code:
Private Sub y1_Change()
If x1.Text = "" Or y1.Text = "" Then Exit Sub
Point1.Left = MapX2Image(CInt(x1.Text))
Point1.Top = MapY2Image(CInt(y1.Text))
End Sub
The x1.Text has value 170625 and Point1.Left has value 488.
I got this nearly every time actually.