Write errors when using non-administrator shared accounts

Question

Dear all,
we're experiencing an apparently weird issue with our Xserve machines. The entire setup comprises of 4 Xserve, all of them running Lion Server, connected together and to the network of our institution through an Ethernet switch.
I've set up an OpenDirectory master on one of these servers and created several shared user accounts for the various people working here (the /Users folder is hosted on that machine and shared across the other three). Users can access any of these machines via VNC.
A few days ago a guy reported to me that he was getting random write errors when attempting to perform basic operations on his shared user folder (e.g., unzipping a file or running a software which write data on the disk). I had a look into it and found that the guy was right. When attempting to extract a zip archive (which, I'm absolutely confident, is a non-corrupted .zip file) from the Terminal - using his account - a few errors came out, like:
error:  cannot create pybrain-pybrain-87c7ac3/pybrain/auxiliary/importancemixing.py
error:  cannot create pybrain-pybrain-87c7ac3/pybrain/rl/learners/meta/meta.py
Every single time I run the unzip command the errors are related to different files.
Weirdly enough, the problem arises only when the user works on one of the three machines that don't host the shared /Users directory. Furthermore, it only applies to non-administrator accounts (if I try to perform the same operation using my admin account everything works smoothly, no matter on which machine I'm working). Promoting that guy to administrator (Server->Users->right click on the username->Edit User->Allow user to administer this server) made the problem disappear. Even more weird, after I removed the flag on "Allow user to administer this server" for that user, he is not experiencing the issue anymore.
What the heck is going on?
Cheers,
Fabio

Answer 1

1.  You can delete the Test1 and Test2 accounts if you log into your Administrator Account. Once in your Admin Account, open System  Preferences > Users & Groups and you will see and be able to delete the Test1 & Test2 accounts.
2.  Leave your Guest account for, well, guest users.  Do not use it in the normal course of events.  When you log out of the Guest account, all the settings, caches, etc. are wiped, as are all files and folders that you may have saved in the Guest account home folder.  The Guest account is truly designed only for temporary, guest use.
3.  Leave your Administrator account for use only for installing programs, doing system administration, managing accounts, etc.
4.  User your named account as your regular account.  It appears to already be a User account.  The primary limitation is you cannot install programs in a regular User account.  This actually helps protect your Mac from viruses and other malware that would need to install software in order to corrupt your system.
5.  You can turn off the need to enter a password when your computer sleeps in System Preferences > Security & Privacy > General.  UNcheck the option called "Require password for sleep and screen saver."