I had the processor for my QS once that Bunns is now using. Tempermental thing, it would prevent the 10.5.8 combo update from validating packages and so the update would fail. There were always other little quirks that popped up as well such as Disk Utility telling me I could not repair permissions.It certainly is a mystery because all of your good advice is what I always do after any installation. At first instance I disable Spotlight, do all the updates, install apps, repair permissions then turn Spotlight back on and leave it to finish. In the Powerbook example, I formatted the drive each time and that Debian install was by itself, not alongside Tiger.
I also sometimes get that recurring problem where the Leopard combo update freezes or if I'm lucky, just hangs for 30 minutes.
At least I now know a sluggish Leopard is cured by a reinstall![]()
I had to pull the drive and do the update from an external case connected via USB to my laptop.
I mention this because it may just be some piece of hardware in your Mac that is just not functioning correctly. Enough to cause problems like this, but no so much that normal use is affected.
Pure speculation on my part.