Run Plan with Observation specifying Autofocus before observing. Periodic AF set to 2 hours. See this in the log.
15-Sep-2010 17:47:22.8: Obs already has autofocus, extend next periodic autofocus
15-Sep-2010 17:47:22.8: Next periodic autofocus moved to 01-Jan-0001 02:00:00 UTC
The date is wrong. Is it a logging issue or is the next Periodic AF wrong?