10.4.10 killed my G5 Xserve

I installed the 10.4.10 Server Combo update and after the reboot I got the Apple logo but no gears and dumped straight into a functional single user shell. Does anyone have any initial thoughts? I attached an external disk and ran the update again which finishes without error. Disk utility says AOK. Repair permissions did find a lot wrong but that didn't solve it. --Mark