I'm getting lots of Samba "too many open files" errors. How can I troubleshoot?
Now I'm no kernel expert, but I think that you might be running into the fact that the default value for the maxflies kernel parameter is 256.  You can show your current value for this parameter like this:

[dwayne | ~] $ launchctl limit maxfiles
    maxfiles    256            unlimited 


I think if you put a line similar to this in a file /etc/launchd.conf (you might have to create the file if it doesn't already exist):

limit maxfiles 2048 unlimited


and reboot, you will see the new value, and hopefully avoid the situation you're running into.

Dwayne