/usr has vanished

[gslink]

There is a bug related to this in FC3.  If you are root and change group 
membership from root to something else and then give rw and execute 
permission to everyone and the directory is a partition then the 
directory will usually appear empty.  If you write anything into that 
directory before rebooting then the directory is messed up.  If you 
reboot first no harm is done.  Is this what happened?