"sh-2.05a#" means that you are using the sh shell as root. That is not necessarily abnormal. What was the prompt you got before? The IOSCSIArchitectureModel has nothing to do with whether the install was done on a machine with SCSI port/card in it. (The message that it can't be found is unusual, however). That kernel extension is important to iBook. It is needed and should load for the optical drive in that machine. Is there media in the optical drive when the Finder crashes occur? Is IOSCSIArchitectureModelFamily.kext in /System/Library/Extensions/ ? Get Info on it in the Finder, and check its ownership. Is it set to Owner: system - read & write; Group: wheel - read only; Others - read only? If IOSCSIArchitectureModelFamily.kext is present, and its permissions are correct, you may have some serious directory issues that fsck can't address. Have you tried using DiskWarrior? Have you reset the PMU? (Sorry if you've mentioned having done this -- I haven't had much time for personal email lately, so I haven't read all the messages about this.) >>> 6. System Issues. I don't remember the finder crashing with 10.1. >>> But >>> it happens every couple of days with 10.2. When I boot into single >>> user mode I get the error "Extension >>> com.apple.iokit.IOSCSIArchitectureModel Cannot be found" and a >>> different prompt than before "sh-2.05a#" Does anybody know what is >>> happening? >> >> This is VERY ABNORMAL. Since you mention that you've repaired >> permissions and run fsck, the only thing I can suggest is that your >> installation is damaged. I would suggest that you try a clean install >> (will not overwrite your old system). Did you by chance copy your >> 10.1 >> system from another machine, one that had a SCSI port or a SCSI card >> in >> it?