Timothy, On Wednesday, March 17, 2010 you wrote: >>> For some reason I cannot fathom, >>> cron.hourly runs twice each hour >>> on one of my two CentOS-5.4 systems, Here comes a very weird idea. I don't know the internals of the cron-daemon good enough to know if this can actually happen. If you have a NTP-job every hour started by cron that corrects the internal time and if your internal clock runs too fast, the system time may be reset every hour so that the cron-job will start twice. As I said, I don't know if cron-daemon has a mechanism that would avoid that problem. best regards --- Michael Schumacher PAMAS Partikelmess- und Analysesysteme GmbH Dieselstr.10, D-71277 Rutesheim Tel +49-7152-99630 Fax +49-7152-996333 Geschäftsführer: Gerhard Schreck Handelsregister B Stuttgart HRB 252024