Occasionally, when running OutOfProcess runtime tests from VS, I get an exception like:

ExcelDna.RuntimeTests.ObjectHandleOutOfProcess.TaskDisposable
 Source: ObjectHandleOutOfProcess.cs line 110
 Duration: 5.4 sec

Message: 
System.Runtime.InteropServices.COMException : The message filter indicated that the application is busy. (0x8001010A (RPC_E_SERVERCALL_RETRYLATER))

Stack Trace: 
RuntimeType.InvokeMember(String name, BindingFlags bindingFlags, Binder binder, Object target, Object[] providedArgs, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParams)
RuntimeType.ForwardCallToInvokeMember(String memberName, BindingFlags flags, Object target, Object[] aArgs, Boolean[] aArgsIsByRef, Int32[] aArgsWrapperTypes, Type[] aArgsTypes, Type retType)
Range.get_Value(Object RangeValueDataType)
<>c__DisplayClass3_1.b__1() line 137
Automation.WaitFor(Func`1 condition, Int32 millisecondsTimeout)
ObjectHandleOutOfProcess.TaskDisposable() line 137