Hi,
I don't know much about target disk mode, but I installed the combo updater on my 12" PB from a disk burned by a really cool fellow who works at a department store in Amsterdam. After rebooting, my machine would "stall" upon the startup screen. I was none too happy as I knew I wouldn't be back home to Japan for another day and a half! I ended up doing software restore, back to 10.2.3. I then reinstalled from Software Update and everything is fine. Although it did seem to hang upon reboot, but finally booted into 10.2.6. At anyrate, what I want to say is that there seems to be a good number of cases similar to this. Hope all is well now.
Cheers,
jaxxe