I have read this knowledgebase article, but would like to know if there's a way to tell exactly which process is causing my Mac not to follow the sleep schedule I have set in System Preferences > Energy Saver. I have narrowed it down to a being a process and will explain why I think so (see below).

I am running OS X (10.6.5) on the new iMac 27" and I am certain it's not the following:

1. The "Wake for Network Access" checkbox in Energy Saver settings (has never been a previous issue)
2. Peripherals (has never been a previous issue)
3. Any active GUI application (all are closed)
4. Additional USB/FireWire drives (none are connected)
5. Bluetooth (it's off)
6. Sharing services (has never been a previous issue)

The symptoms are as follows:

1. The computer doesn't go to sleep at the predetermined time.
2. It will wake up some number of hours after being put manually to sleep (but not within the first few seconds/minutes.)

Is there a specific string I should be looking for in Console? I have tried searching for "wake" and "sleep" but can't make total sense of the results.