Solution to Leopard password problem
I had the same problem. Apple's solution, which I pasted below, is at
http://docs.info.apple.com/article.html?artnum=306840. It worked for me.
Mac OS X 10.5: Unable to log in to account after an upgrade install
Issue or symptom
You may not be able to log in with a user account that has a password of 8 or more characters and was originally created in Mac OS X 10.2.8 or earlier, after performing an upgrade installation of Mac OS X 10.5 Leopard (the default installation type).
Products affected
Mac OS X 10.5
Mac OS X 10.5 Server
Solution
If you can log in or are logged in
Download and install the Login & Keychain Update 1.0 for Mac OS X 10.5 Leopard to avoid the issue later.
If you are unable to log in
you can use these steps instead:
Restart in Single User mode (hold Command-S during startup)
At the prompt, type: mount -uw /
Press Return
Type:
launchctl load /System/Library/LaunchDaemons/com.apple.DirectoryServices.plist
Press Return
Type:
dscl . -delete /Users/[username] AuthenticationAuthority
Note: Replace "[username]" with the affected user account's short name
Press Return
Type: passwd [username]
Note: Replace "[username]" with the affected user account's short name
Press Return
At the "New password:" prompt, type the user's password
Note: It is recommended that the original user's password be used to match the keychain password
Press Return
At the "Retype new password" prompt, type the same password
Press Return
Type: reboot
Press Return
