powerbook startup problem - folder with a question mark ???

[Mauro <mcepeda@ualberta.ca>]

"For the last week or so, when I start the machine instead of having
the yaboot screen appears I get a little folder with a question mark
inside...  This doesn't happen every time I start the machine."


I've had this same problem.  I solved it by reseting pram.
This is mentioned below.  Apple would have u repair the install before
this too so maybe you could fsck, but journaling should have deprecated
this procedure even for OS X.  After, rerun ybin.

http://docs.info.apple.com/article.html?artnum=58042
"Reset parameter RAM (PRAM). 
        
        Reset PRAM, then see if the computer starts up. If it doesn't,
        Repeat step 2.
        
     4. Troubleshoot SCSI devices (if you have them):
        
        Improper SCSI configuration, termination, or cabling may cause
        this symptom. Follow these steps:
        
             a. Shut down the computer.
             b. Turn off all connected devices.
             c. Completely disconnect the SCSI chain from your computer.
                If you have installed a third-party SCSI card, take it
                out of the computer. 
             d. Start up the computer.
        
        
     5. If none of these steps resolved the issue, start up from the Mac
        OS X Installation CD and reinstall Mac OS X. If your hard disk
        is not available (mounted) when started up from CD, contact an
        Apple Authorized Service Provider or Apple Technical Support. "