Ext FW drives causing Netinfo corruption.
 

This isn't a SuperDuper issue but as many SD users rely on ext FW drives I thought I'd mention it.

Repeatedly I was loosing access to my system password and it was caused by a corrupted Netinfo db. After a dig a Apple Discussions it seems that if your FW drives experience a power outage this can in turn corrupt the Netinfo db.

Even though my drives are on a UPS, a hard reboot after a total system hang (i.e not able to eject the FW drives before rebooting) basically causes a power outage for them, this inturn causes corruption, it seems.

The first couple of times I didn't correlate these conditions, with the last time I had just rebooted and the cause became obvious.

HTH