Mac refuses to sleep

Will it sleep if you manually invoke it from the Apple menu?

I also have this problem. Tried all the usual stuff - still refused to give up the insomnia. Decided to install PleaseSleep and get on with my life. Now, apart from a tiny app running in the background - it sleeps!

Do you have a USB hub connected to it? Some hubs will prevent a Mac from sleeping or wake it up immediately.

I have found that using a utility like Onyx ( http://www.titanium.free.fr/) to delete caches works for sleep issues. Before trying it, be sure to read the documentation to understand what you are doing.

I don't know why it works for me - my issue may be different than yours.

are you logged into Facebook using Safari - it may keep your computer awake

This is for a Mac that won't sleep.

Here is Apple's KB article HT1776 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 card.

Also, here is Apple KB article TA2469 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.

Tristan Currier noticed this; "I have a Canon printer(shared) and my imac would not sleep. I opened up printer/fax in system prefs and noticed it said the printer was in use when it was off. Opened up the printer queue and noticed about 7 pending documents. Deleted them all and now it sleeps.
Check the printer queue!"

Allan Jones says "sometimes there is Network activity: launch System Preferences > Energy Saver > "Options" tab and uncheck "Wake for Ethernet network administrator access."

One user has had success, after trying all these tips, using an App. called PleaseSleep. I've never used it though.

Good Luck!  DALE

I've been going crazy with this. It was happening on both an old Pismo G3 running Tiger, and a MacBook running Snow Leopard. I had the same symptoms. Could put to sleep manually, but wouldn't go into auto-sleep. None of the above fixes worked. I found that when I removed my user Preferences folder and restarted (or logged out and back in), a new Preferences folder was created and the computer then went to sleep as expected. So I put back in the Preferences folder and removed individual preferences by trial and error (logging out and back in after each change).

For me, the file that ended up being the problem was "loginwindow.plist" (User>Library>Preferences).
Removing that preference file fixed the problem in both Tiger and Snow Leopard. Hope that might be useful for someone else.

PleaseSleep app solution works only on my MB Alum.
It's interesting when Apple fix this issue.

I've had this same problem for years. I have tried all of the suggestions above. The only thing I found is that my hard drive is, in fact, being accessed every 30 seconds by something, even when no apps are running. I checked Activity Monitor and it seems to be something called "update," with parent process of launchd>kerneltask>kerneltask. I quit the process but it just came back without anything else happening. Anyone know what this could be?

have you tried reinstalling the latest system update from the "combo" update?
This has helped me in the past.

I also have used DiskWarrior.

This no-sleep issue has been the only nagging problem for Mac OS - it does not seem to go away and can be difficult to remedy.

What is the "combo" update? I have had this problem through several versions of OS X (Panther, Tiger, and Leopard), despite regular updates.

My G4 Mac Mini refuses to stay asleep for more than a few seconds when my Epson printer or Epson scanner are connected via a Belkin Mini USB hub. Belkin says it's because the Epsons draw more than the hub's 500mA limit. No problem when the Epsons are connected direct to the Mac.

Is Belkin right that the Epsons are too hungry? Is there a hub which will cope with Epson current demands?

Since you are not running Snow Leopard, why are you posting in the Snow Leopard forum?

It has been so long since I used 10.4 that I can't even remember it any longer.

You really should post over in the correct forum where those using 10.4 hang out.

Allan

Strictly you're right but this problem does not seem to be limited to OS10.4, judging by the postings here. I was hoping that I'd reach a wider audience this way. Perhaps I will.