Fail on drop down box

Hi,

I have experienced this problem multiple time and i cant seem to find a solution, i will insert the error message and log below, as you can see i have tried adding 'wait for *time' steps and also 'wait for *visible' but neither seem to make any difference, this problem is not consistent, it only happens occasionally but the test will fail none the less, i have watched the test and the chosen value is selected correctly and then the step fails.

Any help on this would be great

Jo

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'03/12/2013 14:27:36' - 'NotRun' : 16. Wait for '650' msec.
'03/12/2013 14:27:36' - 'Fail' : 17. Select 'ByValue' option 'CLA' on 'ContentPlaceHolder1DdlAssignmentTypeSelect'
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Failure Information:
~~~~~~~~~~~~~~~
ExecuteCommand failed!
InError set by the client. Client Error:
System.Runtime.InteropServices.COMException (0x80004005): Error HRESULT E_FAIL has been returned from a call to a COM component.
   at mshtml.HTMLSelectElementClass.IHTMLElement3_FireEvent(String bstrEventName, Object& pvarEventObject)
   at ArtOfTest.InternetExplorer.IECommandProcessor.InvokeEvent(IHTMLElement target, String data)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessActionCommands(BrowserCommand request)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessCommand(WebBrowserClass ieInstance, BrowserCommand request, IHTMLDocument2 document)
BrowserCommand (Type:'Action',Info:'NotSet',Action:'InvokeEvent',Target:'ElementId (tagName: 'select',occurrenceIndex: '0')',Data:'onchange--@@--null',ClientId:'Client_7791f341-32cc-42dd-a113-20f964d35ad7',HasFrames:'False',FramesInfo:'',TargetFrameIndex:'-1',InError:'True',Response:'System.Runtime.InteropServices.COMException (0x80004005): Error HRESULT E_FAIL has been returned from a call to a COM component.
   at mshtml.HTMLSelectElementClass.IHTMLElement3_FireEvent(String bstrEventName, Object& pvarEventObject)
   at ArtOfTest.InternetExplorer.IECommandProcessor.InvokeEvent(IHTMLElement target, String data)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessActionCommands(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.Runtime.InteropServices.COMException (0x80004005): Error HRESULT E_FAIL has been returned from a call to a COM component.
   at mshtml.HTMLSelectElementClass.IHTMLElement3_FireEvent(String bstrEventName, Object& pvarEventObject)
   at ArtOfTest.InternetExplorer.IECommandProcessor.InvokeEvent(IHTMLElement target, String data)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessActionCommands(BrowserCommand request)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessCommand(WebBrowserClass ieInstance, BrowserCommand request, IHTMLDocument2 document)
BrowserCommand (Type:'Action',Info:'NotSet',Action:'InvokeEvent',Target:'ElementId (tagName: 'select',occurrenceIndex: '0')',Data:'onchange--@@--null',ClientId:'Client_7791f341-32cc-42dd-a113-20f964d35ad7',HasFrames:'False',FramesInfo:'',TargetFrameIndex:'-1',InError:'True',Response:'System.Runtime.InteropServices.COMException (0x80004005): Error HRESULT E_FAIL has been returned from a call to a COM component.
   at mshtml.HTMLSelectElementClass.IHTMLElement3_FireEvent(String bstrEventName, Object& pvarEventObject)
   at ArtOfTest.InternetExplorer.IECommandProcessor.InvokeEvent(IHTMLElement target, String data)
   at ArtOfTest.InternetExplorer.IECommandProcessor.ProcessActionCommands(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.Core.Browser.ExecuteCommand(BrowserCommand request)
   at ArtOfTest.WebAii.Core.Actions.InvokeEvent(Element targetElement, ScriptEventType eventType)
   at ArtOfTest.WebAii.Controls.HtmlControls.HtmlControl.InvokeEvent(ScriptEventType eventType)
   at ArtOfTest.WebAii.Controls.HtmlControls.HtmlSelect.InvokeOnChange()
   at ArtOfTest.WebAii.Design.IntrinsicTranslators.Descriptors.SelectDropDownActionDescriptor.Execute(Browser browser)
   at ArtOfTest.WebAii.Design.Extensibility.HtmlActionDescriptor.Execute(IAutomationHost autoHost)
   at ArtOfTest.WebAii.Design.Execution.ExecutionEngine.ExecuteStep(Int32 order)
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'03/12/2013 14:27:36' - Detected a failure. Step is marked 'ContinueOnFailure=False' aborting test execution.
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'03/12/2013 14:27:36' - Overall Result: Fail
'03/12/2013 14:27:36' - Duration: [0 min: 0 sec: 484 msec]
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'03/12/2013 14:27:36' - Test completed!