I had this exact same problem. I believe it is because I installed it on the same partition that previously had OS X PB installed, and I did not properly uninstall it.
OS X puts lots of invisible files on your hard drive. In addition to deleting the system files, you must also delete those invisible files. You can do this by formatting the drive (the smart way), or by searching for all invisible files with Sherlock and deleting them.
**NOTE** Do not do this unless you know what you are doing. The preferred method of deleting those files is to format your drive, but if you don't have a backup drive, this is your only option. With Sherlock, search for all of the invisble files on your OS X partition. You can then select the files that you want to delete, and cmd-del them to send them to the trash. You'll want to delete just about all of the invisible files that your find, with the exception of icon files and the desktopDB files. Also, don't delete Norton FS files (so you can recover if you really screw it up.)
After doing this, and deleting all of the visible OS X files, you'll need to reinstall OS X. Everything will work fine.
Again, this is best done by someone who knows what they are doing, as you could cause some damage. Your first choice should be to backup and format the drive.
Let me know if this fixes your problem.
[This message has been edited by Thunderbird (edited 03-25-2001).]