iBook G4 shuts down instead of sleep

Hello,

my own ibook broke. I bought a "new" one and got it opened and replaced the HDD by a WD3200BEVE.

Problem: when I send it to sleep (also choosing "pause HDD when possible" in energy saving preferences) it goes dead until I unplug power chord and put out RAM, if that does not work unplug power chord and unplug battery does it.

Because I haven't tested sleep mode on the new one before upgrading the HDD, I do not know whether it is the HDD. Though I think, one should have heard of the WD causing the problem.

New install of OS 10.4.11 didn't solve the problem.

If I start it from an external Seagate drive via firewire sleep does result in shut down as well.

I posted a question here http://forums.macrumors.com/showthread.p... earlier, but wanted to reconsider a solution.

Anyone who can help?