MacOS – Clean installation of Mac OS X 10.6 using Upgrade DVD

Looks to me like it's syslogd itself causing the problem -- it's been sandboxed away from its data files, so when it tries to access them it generates a sandbox error, which gets handed to syslogd, which triggers it to try to get at its files again... and this repeats as fast as syslogd and sandboxd can go.

Check the contents of /System/Library/LaunchDaemons/com.apple.syslogd.plist (the launchd item that controls how syslogd is launched). It should have a section like this:

    <key>ProgramArguments</key>
    <array>
<!--
    Un-comment the following lines to run syslogd with a sandbox profile.
    Sandbox profiles restrict processes from performing unauthorized
    operations; so it may be necessary to update the profile
    (/usr/share/sandbox/syslogd.sb) if any changes are made to the syslog
    configuration (/etc/syslog.conf).
-->
<!--
        <string>/usr/bin/sandbox-exec</string>
        <string>-f</string>
        <string>/usr/share/sandbox/syslogd.sb</string>
-->
        <string>/usr/sbin/syslogd</string>
    </array>

Note that in the above example (taken from my Mac), the sandbox wrapper around syslogd is commented out. Is the same true on your Mac? If not, re-add the comment markers, and restart syslogd (you can do this with launchctl, but I'd just reboot the machine).

Another note: I took a look in the sandbox profile, /usr/share/sandbox/syslogd.sb, and it looks (to my inexpert eyes) like it does deny mach-task-name and access to /private/var/log/asl/StoreData -- apparently, Apple hasn't debugged (/updated) the profile to match what syslogd actually needs...

There is a thread that discusses using IsoBuster to create an image. You need to back up the entire hybrid disk (at least for 10.6).

Can you access another Mac to do this? If so, in Disk Utility select the drive (not the volume) and click the New Image button on the toolbar to save a DMG as a DVD/CD Master. Funny idea: go to an Apple Store with an 8 GB or higher USB stick, buy Snow Leopard, then use one of the computers there to create the DMG.

Once you have the DMG, rather than using diskutil at the command line, just use Disk Utility and create a 10 GB partition at the end of your drive (under the Partition tab for your drive). Then go to the restore tab and select the DMG for the source and the new partition for the destination. Make sure Erase destination is checked and double-check that you're dealing with the right partition.

Note that I'm using Disk Utility on 10.6 and I haven't worked with 10.4 in a long while. My thinking is that Disk Utility hasn't changed very much and I hope that the features that I'm talking about exist and behave as I would expect on 10.4.

Finally to install Snow Leopard, reboot your computer, hold down the ⌥ key as soon as it starts up (chime) and you should be presented with two options, both with a hard drive icon. The second option should say Mac OS X Install DVD. Select that.

EDIT
Specific IsoBuster instructions from the above thread:

Open IsoBuster -> right click "DVD" on the left side -> choose "extract dvd " -> User Data (*.tao, *.iso)

Name the file whatever you want (ie "Leopard") on the "Save as type" choose ".iso" Click Save and wait for image to be created. After it is finished it will probably ask you to save a ".cue" file as well...go ahead and save it, but you should not need it.