A customers test intermittently fails during Verify element 'xxxx' 'is' visible test step. Here's the stack trace:
'6/9/2014 12:33:13 PM' - 'Fail' : 5. Verify element 'ResearchLink' 'is' visible.
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Failure Information: 
~~~~~~~~~~~~~~~
ExecuteCommand failed!
InError set by the client. Client Error:
System.UnauthorizedAccessException: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
   at mshtml.IHTMLCurrentStyle.getAttribute(String strAttributeName, Int32 lFlags)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessInformationCommands(BrowserCommand request)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessCommand(WebBrowserClass ieInstance, BrowserCommand request, IHTMLDocument2 document)
BrowserCommand (Type:'Information',Info:'ComputedStyle',Action:'NotSet',Target:'ElementId (tagName: 'a',occurrenceIndex: '18')',Data:'visibility',ClientId:'Client_bed03530-638b-4800-abba-5716e7a9c965',HasFrames:'False',FramesInfo:'',TargetFrameIndex:'-1',InError:'True',Response:'System.UnauthorizedAccessException: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
   at mshtml.IHTMLCurrentStyle.getAttribute(String strAttributeName, Int32 lFlags)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessInformationCommands(BrowserCommand request)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessCommand(WebBrowserClass ieInstance, BrowserCommand request, IHTMLDocument2 document)')
InnerException: none.

InnerException:
ArtOfTest.WebAii.Exceptions.ExecuteCommandException: ExecuteCommand failed!
InError set by the client. Client Error:
System.UnauthorizedAccessException: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
   at mshtml.IHTMLCurrentStyle.getAttribute(String strAttributeName, Int32 lFlags)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessInformationCommands(BrowserCommand request)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessCommand(WebBrowserClass ieInstance, BrowserCommand request, IHTMLDocument2 document)
BrowserCommand (Type:'Information',Info:'ComputedStyle',Action:'NotSet',Target:'ElementId (tagName: 'a',occurrenceIndex: '18')',Data:'visibility',ClientId:'Client_bed03530-638b-4800-abba-5716e7a9c965',HasFrames:'False',FramesInfo:'',TargetFrameIndex:'-1',InError:'True',Response:'System.UnauthorizedAccessException: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))
   at mshtml.IHTMLCurrentStyle.getAttribute(String strAttributeName, Int32 lFlags)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessInformationCommands(BrowserCommand request)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessCommand(WebBrowserClass ieInstance, BrowserCommand request, IHTMLDocument2 document)')
InnerException: none.

   at ArtOfTest.WebAii.Core.Browser.ExecuteCommandInternal(BrowserCommand request)
   at ArtOfTest.WebAii.Core.Browser.ExecuteCommand(BrowserCommand request, Boolean performDomRefresh, Boolean waitUntilReady)
   at ArtOfTest.WebAii.BrowserSpecialized.InternetExplorer.InternetExplorerActions.GetComputedStyle(Element targetElement, String style)
   at ArtOfTest.WebAii.Controls.HtmlControls.HtmlControl.IsVisible()
   at ArtOfTest.WebAii.Design.IntrinsicTranslators.Descriptors.VisibleVerificationDescriptor.ExtractData(IAutomationHost targetBrowser, DescriptorValueStore dataStore)
   at ArtOfTest.WebAii.Design.Execution.ExecutionEngine.ExecuteStep(Int32 order)

A test project to reproduce the problem will be attached to the internal bug report.