If you have a label on a usercontrol with the Markup property set to true, the UserControl does not terminate when the hosting form is unloaded - and the hosting form is a secondary window from the Main applications window.

eg.
Place a label on a usercontrol and set MarkUp to true.
Set in code the markup properties:
lblLabel1.MarkupContext.SetMethod Me, "Markup_Click"
lblLabel1.Caption = "Mark up anything"

Place debug.print statements in the Initalize and Terminate events of the control.
Private Sub UserControl_Terminate()  
   Debug.Print "UserControl_Terminate"  
End Sub
Private Sub UserControl_Initialize()
   Debug.Print "UserControl_Initialize"
End Sub

Place the usercontrol on a secondary form and open it from another form.
Watch the immediate window in VB6 - The terminate statement does not get executed.