Do I need to erase my hard drive?

Question

My 15" 1.5GHz superdrive powerbook sometimes won't start up properly in tiger. The screen shows "starting mac os" and then fast it loads (really it doesnt load my user info, doesn't let me log in and leaves me with an aqua blank screen).
The disc permissions are not correct. This is what disk utility says almost each time I check it (so it doesn't repair them even though it says it has!):
Verify permissions for “Macintosh HD”
Determining correct file permissions.
Permissions differ on ./Library/StartupItems, should be drwxr-xr-x , they are drwxrwxr-x
We are using special permissions for the file or directory ./Library/Widgets. New permissions are 16877
Group differs on ./private/etc/authorization, should be 80, group is 0
Permissions differ on ./private/var/log/secure.log, should be -rw------- , they are -rw-r-----
Permissions differ on ./usr/bin/setregion, should be -r-sr-xr-x , they are -r-xr-xr-x
We are using special permissions for the file or directory ./usr/lib/php/build/acinclude.m4. New permissions are 33060
Permissions verification complete
The privileges have been verified or repaired on the selected volume
SO far:
The first time it happened my hard drive was found to be faulty and applecare replaced the HD. When the computer returned from apple, I installed tiger and reloaded my data from a firewire drive (and probably the problem permissions). Every two weeks or so I can't log in and the screen goes to aqua only when I start up. I have reloaded tiger and archived my folders twice and then deleted the old system but the problems remain.
As the permissions seem to be with information outside my user files, could my tiger disc be at fault? I test it before each install and it verifies.
I hope someone out there who knows a lot about computers can tell me what to do as I love macs but have not had much luck with this one since I installed tiger (4.2)
best wishes
Bella

Answer 1

Two things I see in what you posted above are:
- "Verify permissions for 'Macintosh HD'"
- "Permissions verification complete"
These tell me that you have chosen to verify (rather than to repair) file permissions. If you choose to repair permissions (rather than choosing to verify them), the messages,
Permissions differ on ./Library/StartupItems, should be drwxr-xr-x , they are drwxrwxr-x
Group differs on ./private/etc/authorization, should be 80, group is 0
Permissions differ on ./private/var/log/secure.log, should be -rw------- , they are -rw-r-----
Permissions differ on ./usr/bin/setregion, should be -r-sr-xr-x , they are -r-xr-xr-x
should be corrected.
These messages:
We are using special permissions for the file or directory ./Library/Widgets. New permissions are 16877
We are using special permissions for the file or directory ./usr/lib/php/build/acinclude.m4. New permissions are 33060
are not permissions problems. They are status messages indicating that the permissions for these files have been changed for the sake of a system or security update. They will always appear when you repair (or verify) permissions.
One thing you might consider doing is to boot from your Install disc holding down the C key, choosing your language, then go to the Utilities menu in the menu bar and choose Disk Utility. When Disk Utility opens choose to repair permissions, and then choose to Repair Disk. (If any error messages show when you Repair Disk, run it again until no error messages appear.) Again, don't choose to Verify File Permissions or Verify Disk, because these choices don't fix anything.
When you've done this restart your PB and see if things are better.
To answer your questions: Verifying file permissions only causes Disk Utility to report which permissions are out of order. It is unnecessary to choose to verify permissions. Just click Repair File Permissions and permissions issues will be fixed or left alone as is needed.
Some people rarely if ever repair file permissions. It is arguable how much good this does as a regular maintenance task. For troubleshooting, it is sometimes helpful. The conventional wisdom is that you should repair file permissions before you update system software or other software that uses an installer, and then, after you've installed that software and restarted your machine, you should repair permissions again. (Again, may people think this unnecessary, but I always do it, anyway.)
Tuttle