Never seen this before. Make sure installer is up to date, perhaps? The 3.9 CD needs to be in the drive too... Maybe there's a conflict with a WBStartup program?
As a last resort, you could boot from the Emergency Disk.
Sorry I can't offer more. Hope this helps.
Oh, If you use CGX, make sure you have the latest version when you get on to BB2. It's extremely buggy otherwise.
