Incorrect configuration of oplocks (incompatible with the application being used). This is a common problem even where MS Windows NT4 or MS Windows 200x-based servers were in use. It is imperative that the software application vendors' instructions for configuration of file locking should be followed. If in doubt, disable oplocks on both the server and the client. Disabling of all forms of file caching on the MS Windows client may be necessary also.

Defective network cards, cables, or hubs/switches. This is generally a more prevalent factor with low-cost networking hardware, although occasionally there have also been problems with incompatibilities in more up-market hardware.

There have been some random reports of Samba log files being written over data files. This has been reported by very few sites (about five in the past 3 years) and all attempts to reproduce the problem have failed. The Samba Team has been unable to catch this happening and thus unable to isolate any particular cause. Considering the millions of systems that use Samba, for the sites that have been affected by this as well as for the Samba Team, this is a frustrating and vexing challenge. If you see this type of thing happening, please create a bug report on Samba Bugzilla without delay. Make sure that you give as much information as you possibly can to help isolate the cause and to allow replication of the problem (an essential step in problem isolation and correction).