My mac won't sleep.

Some background task is running, let me guess, you have HP software installed? Eg. the software that came with your HP printer, you may need to update the software on HP support.

Please list all of the applications that that are on the computer by using System Profiler.

You may want to try resetting the eMac's PMU as outlined in the Apple Knowledge Base article on replacing the battery:
http://docs.info.apple.com/article.html?artnum=34885

Good luck.

If Ronda 's suggestion doesn't work, read on;

This is for a Mac that won't sleep.
First, read things in Apple doc.#25801 on sleep settings.
Here is Apple doc.#303698 with their tips.
Mine follow;
USB devices and hubs often cause Macs to not sleep or wake quickly from sleep (notably HP printers and scanners, HP all in ones, and Cannon scanners). Disconnect all USB except for keyboard and mouse and try. If it sleeps, add one back at a time testing after each one to find the culprit.

If you've set your Mac to receive faxes, it may not be able to sleep. It might also have a damaged preferences file.

If you use your Mac for faxing, open System Preferences. click Print & Fax, click the Faxing tab, and uncheck the Receive Faxes On This Computer box.

If that doesn't work or you've never faxed on your Mac, go to Finder/Hard Drive /Library/Preferences/SystemConfiguration and delete the com.apple.PowerManagement.plist and com..apple.AutoWake.plist files (if your Mac asks, type your admin. password).

If the latter file isn't present in the folder, go to user name(probably your name)/Library/Preferences, delete the com.apple.systemuiserver.plist file, and reboot your Mac.

Hope this helps!
P.S. One member here reported this (Michael Gleason);
"I have had this problem with my IMac G5. It is surprisingly irritating. LaCie's Silverkeeper backup software was the cause. By default it gave itself permission to wake up the computer to check if a backup was needed. Do you have this or a similar program installed which has scheduled activities including wake-up permissions as an option?"

Dave Hamilton provided this link, xlr8yourmac.com, to a member, which addresses failure of deep sleep with some users that updated and added new FireWire and USB cards.

Also, here is Apple doc.#305262 about PCI cards and sleep.

tomhorvat adds this; After few days of messing around I found out that I had desktop background (wallpaper) set to change every 1 minute.
After unchecking "Change picture..." in system preferences (under Desktop/Screen saver), my powerbook went to sleep all by itself.
Good Luck!  DALE

I had the same problem and was told to get into Disk Utility, select the HD and then click on Verify Disk Permissions and I went a step further and then Repair Disk Permissions if any problems show up that do not seem to get repaired. It worked for me and I had this come up only one other time, but since then I do a regular "verify" and it keeps things cleaner I guess, much like the older Mac "rebuilding the desktop".

Also try to create a new user and log in as that user, does it sleep?

I had this same problem. I found that by deleting all of the HP files from /Library/Frameworks my iMac was able to sleep again.

Please note that this will remove any Printing/Scanning function from your computer if you use an HP Printer and/or scanner. If you are using another model (Canon, Lexmark, Epson, etc.) this will not have any effect. If you end up getting an HP Printer/Scanner down the road, you will have to manually install the drivers, as it won't "just work"

An alternative (that doesn't actually FIX this issue, rather works around it) is to download a program called "NMS sleep assist utility". Do a google search for that, and it will be the first result. I haven't used this software, but I've heard others say it resolves their sleep issues.

Hopefully this info helps. If not, feel free to let me know!

I've done all of the above and my mac still won't sleep as per the energy saver settings. In my activity viewer I can only see that kernel, universal access, window server and pm tool are active. I've replaced the hard drive to a western digital 320 gig because the other drive was failing, but the problem continues. I've repaired disk permissions, deleted HP software, deleted files in library/ preferences. I'm running out of ideas. Help!

I've just recently noted as well, that when I place my computer in sleep mode manually, then wake it up later, I have to wait for dashboard items to reload their settings, as if I had restarted the computer from shut down. Before sleep mode would not affect the dashboard items. Could this be related to my problem.

You can try turning off as many dashboard items as you can bear to do without to see if any of those tools are the culprit. ou can even Disable Dashboard entirely (it's trivial to re-enable it later).

my G4 iMac suffered with this same problem for quite some time. However, a bit of trouble shooting this weekend yielded some positive results. My problem? TimeMachine.

My G4 is connected to my Airport Extreme which has a USB connected hard drive. I luv time machine, but once I turned it off, the G4 sleeps fine ALL THE TIME.

Now, this does "kind of" make sense, but I still think there is something out of wack because my iMac Core Duo handles things just fine.

Now, perhaps we need to consider how often time machine attempts to perform a backup and ensure that your power settings are not too close to the routine time machine backups.

I repaired permissions (and there quite a lot to repair), but that didn't help. So I disconnected my logitech mouse and have tested it a few times. Except for one time, that seemed to work (i.e., the computer went to sleep). Testing it again with the mouse in now.

Hey,
If any music or video or any media for that matter is playing your eMac will not go to sleep.

Matthew Knice

Hi, Before anyone goes crazy troubleshooting with sleep issues first try resetting the SMC. It basically consists of unplugging everything including the power source and then plugging back in after 15 seconds. It fixed all my sleep issues and saved me from a hugh headache.

BUT read the instructions: http://support.apple.com/kb/HT1543?viewlocale=en_US