My problem was NOT ONLY with ~/.ICEauthority being owned by root, but also that there were two additional ~/.ICEauthority* files created for some reason.
Changing the ownership AND renaming/removing those two new files fixed MY problem:
Something bad obviously happened and I figured an important change must have happened so I checked what was modified in the last 10 minutes:
I compared the files that showed up with files of the same name on a different, working PC, which had the same OS (Ubuntu 9.10) and also checked their permissions. On the bad PC:
find ~/ -mmin +0 -mmin -10
Only the problem PC had the 2 extra (empty) files compared to the working one:
ls -la ~/.ICE*
which gave me something like:
-rw------- 1 root root 45846 2010-05-08 21:09 /home/myuser/.ICEauthority
-rw-r--r-- 2 myuser myuser 0 2010-05-10 13:28 /home/myuser/.ICEauthority-c
-rw-r--r-- 2 myuser myuser 0 2010-05-10 13:28 /home/myuser/.ICEauthority-l
~/.ICEauthority-c and ~/.ICEauthority-l
Also, the ~/.ICEauthority file was owned by root only on the bad PC.
I changed the ownership to match the working PC and renamed the 2 strange new files:
After that, I didn't get the error anymore. Although I still don't really know what those files were for, I wonder if they were "stale locks" for ICE Authority.
mv -iv ~/.ICEauthority-c ~/.ICEauthority-c.backup
mv -iv ~/.ICEauthority-l ~/.ICEauthority-l.backup
sudo chown myusername:myusername ~/.ICE*
In my case, both times I had this problem I think I was messing with opening extra displays on the same PC using the commands "xinit" and "ssh" (also, "xpra" and "screen" may have done something too, but I'm not sure). I think this is why my problem differed from others'.
Anyway, hope this helps someone. Have a great day! ^^/