« Troubles upgrading to Leopard?

I had few troubles upgrading to Leopard. 
Basically the Mac didn’t start anymore(*). 
The problem was on the hard disk nodes, so I reckon a disk check before trying to upgrade. If there are problems, the Mac disk utility will not help you, better to try with DiskWarrior.

If you’re reading this post because it’s too late and you’re in troubles, I fixed the system installing Leopard to my firewire disk, installed there DiskWarrior and fixed the disk from there. (credits to Luca for the pragmatic solution).

(*) I was sweating blood since the Lacie Backup utility ”forgot” to backup all my iTunes library! :’-( Now I feel much safer with the time machine, great app.