Been having an odd issue lately with my 1.42ghz iBook (10.4.8):
When booting up it will kernel panic for the first 4-6 starts, and then start up normally. Works fine from a safe boot. It doesn't usually wake from sleep either (seems to be on but screen stays black). I've tried disk utility, fsck, and reinstalling the system (archive/install, not a clean wipe.
Any ideas?