From the newsgroups...if you accidentally did a sys-unconfig before applying the patch.  :)

1. vi /etc/.sysIDtool.state and replace all 1's with 0's.
2. touch /etc/.UNCONFIGURED
3. reboot and when the machine comes back up, it should run sysidtool
   and ask you for the info.

Then, make certain you download the sys-unconfig patch from
sunsolve.sun.com.  

The patch number is: 109318