samba - Aug 2002 - XP file locking

I've been having some problems with Windows XP and Samba 2.2.5.

Symptom on client side:  open a file, and everything works fine until the user
tries to save it.  Error message varies - usually some form of "permission
denied."  Intermittent.  Usually, everything is OK.

On the server side, I was getting oplock errors that coincided with the client
error, so I turned off oplocks.  The problem remains, though I can't seem to
find error messages in the log files.

Any suggestions?

Thanks,
Jim