What is more annoying than mcx_cache when dealing with clients in a Mac OS X Server lab? Have you recieved a window saying that you are not permitted to log in? And you are 100% sure that everything is set up correctly; login might even have worked for days until this shows up!
In most cases (atleast here), this is because of this annoying cache file, storing information about your Mac OS X Server. Destroying this directory from NetInfo has been 100% painless in all ways here, as it is re-created again at next log in.
For some time, I did this manually by destroying it from the NetInfo Manager app, but as my school got more and more X clients, and it was taking up a lot of time, I had to find a better solution to this. The solution was to create a cron script to run a command that did this automatically. I use the great app CronniX to make the cron script. From this app, choose to manage the System User's crons. Add a new one, and choose run time yourself; I set mine to run one time each hour. The command to execute is this:
sudo niutil -destroy . /mcx_cache[robg adds: I can't vouch for this one, having no access to nor experience with Server...]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030916114028213