Failed to start a new STA thread

Hi!

We are having some really weird failures where a .NET 1.1 dll fails to start a new STA thread. The weird part is that the caller does not get any kind of exception (except the one that we are throwing because the resetEvent.WaitOne won't succeed within 5 minutes).

The method is called from a Biztalk 2004 orchestration. The worker thread does use a 3rd party com-dll that won't work in MTA.  

Here is a short code snippet to show what we are trying to do.

    public abstract class MyBaseClass
    {
        private ManualResetEvent resetEvent = new ManualResetEvent(false);

        protected void Execute()
        {
            try
            {
                Thread STAThread = new Thread(new ThreadStart(RunCommand));
                STAThread.ApartmentState = ApartmentState.STA;
                STAThread.Name = "STA worker";

                STAThread.Start();

                if (!resetEvent.WaitOne(new TimeSpan(0, 0, 5, 0, 0), false))
                {
                    throw new ApplicationException("Thread did not respond within timeout limit");
                }
            }
            catch (Exception ex)
            {
                // dumping of the exception to the eventlog omitted for brevity
                throw;
            }
        }

        private void RunCommand()
        {
            try
            {
                /*
                 * this  is where the real work is done
                 */ 
            }
            catch ( Exception ex)
            {
                // dumping of the exception to the eventlog omitted for brevity
                throw;
            }
            finally
            {
                resetEvent.Set();
            }
        }
    }

I've added a lot of debugging code the that function. It shows that most of the time the function works fine but a few times a day the child-thread just don't start.

We've also noticed that quite often it takes a few seconds before the runcommand delegate really does anything.

Do you have any idea what could cause this and how to investigate this further?

With regards

Tapio Kulmala