The process cannot access the file

I see this error: 
The process cannot access the file '\Contentfiles\logos\1.html' because it is being used by another process.
 MY code is:

 Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
         If DropDownList1.SelectedIndex = 1 Then
        Dim fp As StreamWriter
        fp = File.CreateText(Server.MapPath(".\Contentfiles\logos\") & "1.html")
        fp.WriteLine(FCKeditor1.Value)

        fp.Close()

          End If
        If DropDownList1.SelectedIndex = 2 Then
            Dim f ...