I got hit by a problem on a freshly installed virtual machine using a slipstreamed SP1 installation and promoted to a domain controller. Two events were appearing in the event log which were unexpected.

Source: MSDTC Event ID: 4143 Information
MS DTC has detected that a DC Promotion has happened since the last time the MS DTC service was started.

followed by

Source: MSDTC Event ID: 53258 Warning
MS DTC could not correctly process a DC Promotion/Demotion event. MS DTC will continue to function and will use the existing security settings.

To resolve this, go through the following steps:
- Start/Administrative Tools/Component Services
- Navigate the tree view on the left to:
    - Console Root
     - Component Services
      - Computers
       - My Computer
- Right click on "My Computer" and select properties
- Select the MSDTC Tab
- Under "Transaction Configuration" near the bottom, click "Security Configuration"
- On the Security Configuration screen, just click OK - don't change anything.
- Back on the "My Computer Properties" screen, click OK again to dismiss
- Right click on "My Computer" in the tree view and select "Stop MS DTC"
- Right click on "My Computer" in the tree view and select "Start MS DTC"
- Close the Component Services snapin.

All should now be well again. Hope this helps someone.