Why does Root need passwords?

[Andreas Eichner <aeichner@villa-grunert.dyndns.org>]

Hi there,

after ca. 1 month uptime I had a bad system crash due to a hardware 
failure. I encountered strange behaviors and after some reboots I set 
"forcefsck". Several errors where found which my ext3 did not realize by 
journalling (and now I know why Ext3 is still experimental).

And since this day I need passwords when changing from root to another 
user by doing "su <username>" - not funny, since some init-scripts want 
to change to lower privileged users (like distributed-net).

How can I recover this situation?

Thanks a lot!