[IFLY2HIGH]

I have a 2008 Mac Pro, and when I upgraded to Mountain Lion this week, my system no longer wants to sleep. I select sleep from the apple menu, and the screen turns off, but I never hear the hard drive, fans, and power light do their normal sleep thing like they used to. The fans are still on and the light is still steady, it's not doing the slow flash telling me it's sleeping. Nothing in my system has changed with the exception of installing mountain lion, 10.7.5. Only USB devices I have plugged in the the keyboard and mouse. No other hard drives installed, and the NVIDIA GeForce GTX 285 is the only expansion card I have, and it's been in there for years. I have reset the PRAM but it still just sits there.

I checked the hibernate mode and it's set at " 0 ".

Suggestions?

[Mike Wuerthele]

No new software besides the OS keeping things awake? Is the machine re-spotlighting after the update?

[IFLY2HIGH]

I let it do all that stuff the first day overnight, and it's been several days now and it's all quiet on the spotlight front. I can even quit all my apps and still won't go into sleep.

[reader50]

Insomnia is usually caused by some hardware item that doesn't support sleep. Or a missing driver for said item. Does your monitor have a USB hub built in? If the monitor has a USB cord, try unplugging that. Or pull the monitor entirely, then sleep the MacPro by pressing the power button. Listen for the drives and fans.

You can do the same with keyboard, then with mouse. Unplug one at a time, then sleep computer via the power button. Try other cable connections, like the ethernet. This will be easier to diagnose if you can narrow the cause.