This is powerpc; not an intel chip mac. (I'm trying to help out someone else.)
Can boot and restart for a number of times and then suddenly, it won't turn on at all. Wait a day or so and it'll start right up and work.
As long as it's left running, it works. Sometimes, shutdown and not unplug the power cable and it won't startup again. Wait a couple of days and it'll work.
Tried different power cables, power strips, etc.

Any ideas?

thanks

Charlie

Did you ever try repair permissions, with Disk Utility ?

Did you try "reset PRam" ?
at startup hold down CMD OPT and P and R keys
after 3rd BONG let go and see if that helps.

after that, you could try Safe-mode, Single User Mode, Applejack, Disk Warrior... there's more too..