eMac won't sleep

[robinbaxter]

I have a brand new (2 weeks) eMac with a 1.42 GHz processor, 512 MB DDR SDRAM, and OS X 10.4.4 installed. After creating an Automator task (Power Tip Of The Month from Sept. 2006 MacWorld magazine, Turn Your Mac into a Musical Alarm Clock) the sleep mode stopped working. I can manually sleep the computer from the Apple dropdown menu but it will not sleep from the System Preferences/Energy Saver settings. This happened last week after installing a WeatherBug Lite application, which puts current weather conditions in the toolbar. Sleep resumed after removing that application. I have removed the Automator task and all startup items. Apple techs had me reset the Power Management Unit and trash the Power Management .plist from the System Management folder but this did not fix the problem. My only peripherals are a Canon Pixma MP760 printer/scanner and a Rocstor 160 GB Firewire external hard drive. Any help will be appreciated.