I have been using Mandriva for 5 years, currently with 2010.2 installed, but what's 'under the hood' remains a mystery to me.
When I switched on my computer this morning I could not log in to my user accounts, and got the messages:
"Could not update ICE authority file /home/myusername /. ICE authority"
"There is a problem with server configuration (/usr/lib/gconf-sanity-check-2 exited with status 256)" (actually the message was in Spanish, but this was the gist of it).
I can log in as xguest and can create new users, but my existing users and all my data files have vanished.
I have found reference to similar problems, but none of the suggested solutions seems to work for me.
How can I recover my user data files (if I can)?

User should be able to write that file.
change permissions as root and check.

When you say "that file", do you mean ICEauthority?

At this point I am concerned that I have lost all my data files, as my user folders have disappeared from the /home folder.

Yes .ICEauthority in /home/username directory.
Your files may be encrypted?

As I said, all users and data files disappeared. There was no /home/username directory. The directory and its contents simply vanished. I know the ICEauthority file is stored in the user directory, but what happened to the user directory? It disappeared with all of its contents (including the ICEauthority file).

Thank you for taking the trouble to reply, but in the meantime (a week has gone by) I have used "Photo Rec" software to recover my files quite successfully, although the original file names were lost, and have reinstalled Linux from scratch.

I don't know what happened. I have searched high and low but have found no explanation for this problem. It has meant a lot of wasted time, although luckily I have been able to recover my user data files.