Someone removed some brakets here:
cb_1.x = li_widthmidpoint - (cb_1.Width +20) + (cb_1.width/2)
This results is an invalid position of the first button.
Change it back to
cb_1.x = li_widthmidpoint - ((cb_1.Width +20) + (cb_1.width/2))
or change it to
cb_1.x = li_widthmidpoint - (cb_1.Width +20) - (cb_1.width/2)
I think there should be also a little more space at the right side of the window:
If (cb_print.Visible=False And cb_userinput.Visible=False) Then
This.Width = mle_message.X + mle_message.Width + SEPARATOR + 30
Else
This.Width = mle_message.X + mle_message.Width + cb_print.Width + (SEPARATOR *2) + 30
End If
Change 30 to 60 would be better.