The system is a PowerPC Mac Mini running MacOS Tiger 10.4.11.
When I login (I'm the admin), everything seems fine - until about 10-15 minutes later. Then the system goes into sleep mode. Each time I try to wake the system up - I can barely log in before it goes to sleep again. Sometimes I don't have enough time to enter my password (from the screen saver).
If I shut down and restart, then I have that 10-15 mins again - until it again goes to sleep.
I checked the settings in the Displays and Energy System Prefs. I looked at Accounts and at Screen Saver System Prefs; no times seemed to be present. I've already reset the PROM and other things (as part of an earlier problem shooting session).
If I don't log in at the desktop, things seem to be fine. Nothing in .profile, /etc/profile, or /etc/bashrc seems to stand out.
Right now, the system is hardly usable; can someone help? Many thanks...
EDIT: Thanks for the migration. I only just found out about superuser.com; fantastic!
PS. I should mention that the sleep occurs even if Caffeine is toggled to "no sleep", and even if Jiggler is running (both programs set to keep the system from sleeping...)