This is an application issue, not an OS issue; every application is responsible for notifying the OS if it is busy and thinks that the computer shouldn't consider itself idle for sleep purposes. Some applications will prevent sleep while doing things, some won't. You can try switching applications, or you can run something in the background that will keep it awake (something like DVD player running a DVD would work, for example, though an odd workaround). Or, as somebody else suggested, set the display and computer sleep separately; there's not really anything horrible about your computer being on a few extra hours, as long as the display is off. Even if the display were on, there wouldn't be anything wrong with it, except that your maximum brightness would decrease over a long time if you did this repeatedly. John O'Brien <Obi-John at Short-Trooper.org> writes: > Does Mac OS X not consider Internet downloading via AirPort sufficient > activity not to go to sleep? My 1GHz TiBook (SuperDrive) will go to > sleep, terminating the AirPort connection, even when there is wireless > network activity. Is this normal? Is there any way around it (aside > from setting sleep to "never")?