I just tried

set oplocks level 2 enabled = off

and I'm still getting messages like this on the server console:

5-23-2006 <time> COMN-3.23-592 [nmID=F000A]
Station 57 (task 5) times out waiting for an op-lock on file < filename>
held by station 24

What does this mean and do I need to have users reboot after making this
change on the server?

In particular, will changing the client-side setting of cache or commit make
a difference?