10.5.7 not finishing installing

[1800collect]

We've been at the 20% mark for over 30 minutes and it is not proceeding. We're afraid to manually restart the computer in fear we'll screw something up. What do we do?

 

[ziggyonice]

I've seen this happen before. In most cases, it's fine to shut down by holding down the power button. When the machine starts back up, it'll re-install automatically.

That's what I'd do, at least.

 

[JediMeister]

If you have been backing up with Time Machine, there's nothing to be concerned with because you can always revert it back to before the update. Restarting should be relatively safe, but if in doubt, locate your install discs so you can try an archive and install preserving users and settings if something breaks.