Security update now password fails

[surfsidesix at earthlink.net]

A friend does a security update in Jaguar, runs the installer and it 
does it's thing.

Tells friend to restart. He does, but now his old password doesn't work.

BUT.....

The hint that comes up after three tries is still the same.

Huh?......

I don't have an OS X box in front of me so I can't duplicate his problem.

How do I get around the password; delete it, change it or whatever?

Can I use the Jaguar install disk to get around it?

If it is something I can just delete, can I get to it from 9.2?

I want to have all my options in order before I traipse all the way 
across town and fiddle with his machine.

TIA,

Cobey

His box:

Quicksilver G4 867MHz

Jaguar 10.2