I am the system administrator.
I have a system that was built with a default install which resulted in everything in a single file system except for /boot
wrote some scripts to split out: /home, /usr, /var, /opt, and /tmp to separate file systems/logical volumes it looks like it ought to work,
There's plenty of space in all the filesystems and I can log via ssh and have write access in my home directory. Logging in via ssh did result in a new .Xauthority file being automatically created, but that did not help.
Googleing around I saw a thread where the user was actually out of disk space, but before that was established somebody asked if /home was on a different filesystem from /, but what to do in that case never came up.
Another google thread suggested looking in .xsession-errors, but I don't have one.
I've found irrelevant ubuntu suggestions regarding ubuntu only packages.
Still googleing