Charlie's 667 keeps going to sleep

[Simon Chapman]

It never rains but it pours... My son's 667 keeps going to sleep
unexpectedly. It happens when booted in 9.2.2 or 10.2.3. It happens when
using trackpad or usb mouse. It happens when running off battery or mains.
It happens when Energy Saver prefs have been trashed and set again to Never
Sleep. It happens even though Apple allegedly fixed this problem a year ago
by swapping out the logic board. Maybe 8 or 10 times a night it happens...
during games, or while any of his various applications are in active use -
the screen goes black without warning and the HD spins down. A click brings
it back albeit fairly slowly but this is no way to carry on. We've zapped
PRAMs, reset Power Manager (which does seem to help for an hour or two
until the blackouts return), swapped batteries, swapped mains adapters,
installed fresh systems, run diagnostics, scratched our heads...... Any
help out there...? Otherwise back to Apple it goes thanks to an extended
warranty. TIA.

Simon
(Not having a good TiBook week)