Error 80080005 trying to do basic COM Automation from Windows Service

I wrote a simple Windows Service in C#, installed it and have it run as System.

I want to instantiate a COM object from the Microsoft Office Communicator Automation API:

using System.Collections.Generic;
using System.Text;
using CommunicatorAPI;
using System.Runtime.InteropServices;

namespace MyService
{
  class OCSIntegrationUtil
  {
    private static Messenger _messenger;

    public static void Register()
    {
      _messenger = new Messenger();

      _messenger.OnContactStatusChange += new DMessengerEvents_OnContactStatusChangeEventHandler(_messenger_OnContactStatusChange);

      _messenger.OnMyStatusChange += new DMessengerEvents_OnMyStatusChangeEventHandler(_messenger_OnMyStatusChange);

      IMessengerContactAdvanced localUser = (IMessengerContactAdvanced)_messenger.GetContact(_messenger.MySigninName, _messenger.MyServiceId);

      System.Runtime.InteropServices.Marshal.ReleaseComObject(_messenger);
      _messenger = null;

      System.Runtime.InteropServices.Marshal.ReleaseComObject(localUser);
      localUser = null;
    }

    static void _messenger_OnMyStatusChange(int hr, MISTATUS mMyStatus)
    {
      // Your code to work with presence goes here...
      Console.WriteLine("\n***OnMyStatusChange***");
    }

    static void _messenger_OnContactStatusChange(object pMContact, MISTATUS mStatus)
    {
      // Your code to work with presence goes here...
      Console.WriteLine("\n***OnContactStatusChange***");
    }
  }
}

However, when the service starts, it generates an Error in Event Log:

Retrieving the COM class factory for component with CLSID {8885370D-B33E-44B7-875D-28E403CF9270} failed due to the following error: 80080005.
   at MyService.OCSIntegrationUtil.Register()
   at MyService.Service.Start()

I am successfully executing the preceding source code when I execute it in the context of a Console Application (i.e. I get OnMyStatusChange and OnContactStatusChange written at the screen whenever I change my status).

I'm familiar with programming, but not much with Windows Service programming. Anyone has a clue of why I get this error? Is it possible at all to do this in a service, or I am losing my time?