If you are the victim of the subject condition, it may be you used a very strange upgrade path,
such as NTW --> SP1 --> NTS --> SPx or some such unusual upgrade path (maybe involving and eval or NFR version).

In any case, the following may resolve your problem:

1. Quiet the network. No activity of any type should be happening.

2. Use Regedt32 to navigate to:

       HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows

3. In the right hand pane, select the ShutdownTime value name, a type REG_BINARY, and delete the value name.

4. Exit Regedt32.

5. Wait 5 minutes, get a cup of coffee.

6. Power the machine off. DO NOT shutdown.

7. Boot the computer and once fully up, do a normal shutdown.

I hope this fixes the problem for you.