Filesharing problems

I discovered that the Mac box is no longer visible from the PC, so it looks like I've got some Samba problems under Leopard. Looking at the logs in the Console app, it looks like smbd keeps exiting immediately after startup. Running from the command line also fails:

/etc:smbd -i -S
smbd version 3.0.25b-apple started.
Copyright Andrew Tridgell and the Samba Team 1992-2007
WARNING: The "printer admin" option is deprecated
Failed to open /private/var/db/samba/secrets.tdb
ERROR: we did not create the shmem (owned by another user, uid 0, gid 0)
ERROR: failed to setup profiling

No clue on this one—the only hint out there looks to be unrelated (shutting down Apache makes no difference).