I encountered this problem more than once. I have a number of ToolStrip containers on my form and at some point (I think it happens after I change images on toolstrip buttons) all the controls on toolstrips disappear. For some mysterious reason lines like "Me.ToolStripContainer1.Items.AddRange(New System.Windows.Forms.ToolStripItem() {<items list>})" are removed from the code (in Form1.Designer.vb). The items are initialised, but they are not added to the toolstrip. I'd like to know how to prevent this from happening.