Vista hangs (reboot loop) installing update 3 of 3

I had this happen recently (10/20/09). I could not tell what the problem was, nor could I tell what update was failing. I tried safemode boot, last known good config, and repair, none worked.

To resolve this I booted off the Vista installation media, and selected repair. It tried to automatically repair startup configuration, and then came back saying it could not. One of the options was to go into advanced repair options. Chose that. Then chose command prompt. At command prompt:
>cd c:
>cd windows
>cd winsxs
>del pending.xml

Once the file was deleted, rebooted system. System went back to installing update 3 of 3 but this time it worked.