27" iMac won’t wake up from sleep

Problem

When you put your 27″ iMac to sleep, it does not wake up.

Cause

This applies to a recent batch of 27″ iMac models with Snow Leopard that have been sent out with this problem.

Solution

Reinstall Mac OS X from the Install DVD:

1. Insert the Mac OS X installation disc.
2. Double-click the Install Mac OS X icon. The Welcome pane appears, followed by the License Agreement.
3. Read and agree to the software license agreement.
4. In the pane where you select a disk, select your current Mac OS X disk (in most cases, it will be the only one available).
5. Click Install.