> 1. What is your output of testparm? No errors or warnings, apart from rlimit_max: increasing rlimit_max (1024) to minimum Windows limit (16384) > 2. If you run top, are any Samba related processes (winbindd, smbd, etc) consuming excessively high amounts of CPU? I did not observe this, although the machine was running at a load of 1+ with no apparent culprit. > 3. Have you considered cranking up or enabling logging to obtain some useful log info? Considered, yes, executed, no ;-) > 4. Has this Samba server run correctly in the past? If so, has anything changed recently? Yes, it always has, and works perfectly with -33. Timestamp on smb.conf shows it was last modified under 3.6.23-24, followed by updates to -25, -30, -35. With trial and error, I settled on -33 as last working version. > 5. You probably already know this but Samba 3.6.x is ancient. Have you considered running Samba 4.x? Centos 6 repos have Samba 4.2.10 packages. Samba 4.x is an intimidating piece of software. If it can perfrom the same function and use the same config, I'm willing to try it. > 6. Have you checked for corrupted Samba *.tbd files? Consider running tdbbackup: > https://www.samba.org/samba/docs/man/manpages-3/tdbbackup.8.html See 4. .tdb files look ok and tdbbackup gives no errors.