title: I get exception of ULS log of sharepoint when Impersonation in SharePoint
body: <p>this is my code:</p>
  
  <pre><code>SPWeb oWeb = SPContext.Current.Web;
  SPUserToken token = oWeb.AllUsers[@"SHAREPOINTSYSTEM"].UserToken;
  using (SPSite elevatedSite = new SPSite(oWeb.Site.ID, token))
   {
      using (SPWeb elevatedweb = site.OpenWeb())
       {
  
       }
   }
  </code></pre>
  
  <p>i run this success. But i see in ULS log of sharepoint, have exceptions as: "Don't dispose object web". I think when i use "using" for proccess, SPSite and SPWeb auto release memory.</p>
  
  <p>Please help me in this problem</p>