I just installed the 10.1.1 update over 10.1 because I like living on the edge. Well, I fell off. My computer would not start up. It kernal panicked just after the login screen after 3 consecutive reboots. So I reinstalled 10.1 (5L14) over the 10.1.1 install and everything came back just fine. No problems. Whew!
G4 dual 500, 1.06 GB RAM, ATI Radeon, OS X 10.1, 9.2.1, DVD-RAM, Ultra160 dual channel SCSI.