If you use a MDI form, then this needs to be unloaded:
Unload myMDI
In the MDI's QueryUnload event, use a loop to unload all child forms:
Dim frm As VB.Form
For Each frm In VB.Forms
If Not TypeOf frm Is MDIForm Then
Unload frm
End If
Next frm
Then, make sure you also unload any designers (DataReport, Crystal Reports, etc) and Close/destroy any objects (Such as class objects, Connections, etc - also you need to explicitly close and destroy these in each form's Unload event, if they were declared at form module level)
If Not Conn Is Nothing Then
If Conn.State = adStateOpen Then Conn.Close
Set Conn = Nothing
End If
Once everything is Unloaded and Destroyed, then you should be OK.