Apple Portables: Progress bar appears after waking from sleep

The progress bar shown above indicates that the computer is waking from Safe Sleep. Safe Sleep ensures that data stored in main memory will not be lost should the computer shut down due to a loss of power during sleep mode. Prior to your computer entering sleep, Safe Sleep automatically saves the contents of main memory—such as desktop settings, open applications, and other work in progress—to the hard drive. In the event the battery becomes completely depleted while the computer is asleep, the computer will shut down. But when a power adapter is connected or a freshly charged battery is installed, the computer can be restarted. Press the power button as if turning the computer on and it will automatically return to the desktop state that existed prior to entering sleep. This means that applications and files will remain exactly as they were prior to the computer being put to sleep, making it easy for you to continue with your work.