问WatiN UnauthorizedAccessException错误

EN

Test Test.IndexTests.Can_Do' failed: WatiN.Core.Exceptions.ElementNotFoundException : Could not find INPUT (hidden) or INPUT (password) or INPUT (text) or INPUT (textarea) or TEXTAREA element tag matching criteria: Attribute 'name' equals 'q' at http://www.google.com/ (inner exception: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED)))
  ----> System.UnauthorizedAccessException : Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
    at WatiN.Core.Element.get_NativeElement()
    at WatiN.Core.Element.GetAttributeValueImpl(String attributeName)
    at WatiN.Core.Component.GetAttributeValue(String attributeName)
    at WatiN.Core.Element.get_Id()
    at WatiN.Core.Element.get_IdOrName()
    at WatiN.Core.TextField.TypeText(String value)
    Class1.cs(23,0): at Tests.Can_Do()
    --UnauthorizedAccessException
    at mshtml.IHTMLElementCollection.tags(Object tagName)
    at WatiN.Core.Native.InternetExplorer.IEElementCollection.GetElementsByTag(String tagName)
    at WatiN.Core.NativeElementFinder.FindElementsByTag(String tagName)
    at WatiN.Core.NativeElementFinder.<FindElementByTags>d__0.MoveNext()
    at WatiN.Core.ElementFinder.FindFirst()
    at WatiN.Core.Element.FindNativeElement()
    at WatiN.Core.Element.get_Exists()
    at WatiN.Core.Element.<>c__DisplayClass9.<WaitUntilExistsOrNot>b__8()
    at WatiN.Core.UtilityClasses.TryFuncUntilTimeOut.Try[T](DoFunc`1 func)

0 passed, 1 failed, 0 skipped, took 43.44 seconds (NUnit 2.5.5).