gdm login problem

["Thomas H. George" <tom@spininternet.com>]

Suddenly I can no longer login to gdm.  When I enter my user name the
screen goes blank then returns to the login screen.  I created an new
user and when I tried to log in as this user the screen went blank after
I entered the new user's password.  I still can login at any of the
terminal screens with either my user name and password or the new user's
name and password.

At one point there was a message /dev/null permission denied.  The
permissions were 666 which seemed like it should be ok to read and write
to /dev/null but I changed them to 777 to be sure.  Then I no longer got
the message but the logins failed as above.

Anyone know what I have messed up?

Tom