Open Firmware: Password Not Recognized When It Contains the Letter "U"
If you used Open Firmware Password utility to create a password that contains the capital letter "U", your password will not be recognized during the startup process (when you try to access Startup Manager, for example).
Your Open Firmware password is not recognized during startup.
Don't use a capital letter "U" when setting up an Open Firmware password. Change your password if necessary.
For more information, see technical document 106482, "Mac OS X 10.1, 10.2: How to Set Up Open Firmware Password Protection".