logon problem

[Tom Preston]

I have ubuntu with gnome installed on a p4 1.8ghz clone.  Nice stable
install for weeks.  Now when I try to log on with my admin account, I
get the following error.

Your session only lasted less than 10 seconds.  If you have not logged
out yourself, this could mean that there is some installation problem or
that you may be out of disk space.  Try logging in with one of the
failsafe sessions to see if you can fix this problem.

I can log in the terminal window with failsafe but don't know what to do
to fix it.  The error message listed in /.xsession-errors starts with

Unable to find transport:tcp
IceTransmkdir: ERROR: euid !=0, directory /dev/X will not be created
IceTransmkdir: ERROR: cannot create /dev/X
IceTransPTSOpenserver: mkdir(/dev/X) failed, errno=13
IceTransOpen:transport open failed for pts/(computername):


I can log on with a non-admin account and it works fine.

What happened and how do I fix it.  I'd rather not re-install
everything.

Tom