My 2008 MacBook Pro won't go to sleep

Please test after taking each of the following steps that you haven’t already tried:

Step 1

Take all the applicable steps suggested in this support article, including the ones under the heading "If the previous steps don't work." That's the starting point for any further effort to solve the problem.

Note that, as stated in the article, the computer will not sleep if some sharing services are enabled. From the menu bar, select

 ▹ System Preferences... ▹ Sharing

Turn off all sharing services.

Also note that the "external devices" referred to in the article could include Bluetooth devices, other than those made by Apple. If you're using a MacBook, MacBook Air, or MacBook Pro, or if you're using a desktop Mac with a wired keyboard and mouse, turn Bluetooth off to test.

Step 2

If iTunes Music Sharing or Home Sharing is enabled, disable it or quit iTunes. Do the same with any third-party applications that have a similar feature.

Step 3

Select

 ▹ System Preferences... ▹ Accessibility ▹ Speakable Items: Off

Step 4

Select

 ▹ System Preferences... ▹ Bluetooth ▹ Advanced...

and uncheck both boxes marked

Open Bluetooth Setup Assistant at startup if...

Step 5

Reset the printing system.

Step 6

Back up all data.

Triple-click the line below on this page to select it, then copy the text to the Clipboard by pressing the key combination command-C:

/var/vm

In the Finder, select

Go ▹ Go to Folder...

from the menu bar and paste into the box that opens by pressing command-V. You may not see what you pasted because a line break is included. Press return.

A folder named "vm" should open. Inside it, there may be a file named "sleepimage". Move that file, and only that one, to the Trash, but don't empty yet. You'll be prompted for your password. Close the folder window.

Restart the computer and empty the Trash.