GDM could not write my authorization file

This problem will occurs in linux machines due to out of diskspace.
To solve the problem we have switch to console (ctrl+alt+f1)
log in

do a 'df -h', this should list out space of all your mount points like:

Code:

Filesystem Size Used Avail Use% Mounted on
/dev/sdb1 68G 16G 49G 24% /

Now if your / space is full, you would have to free up some space. If you
have your /home on a diff partition, check that too.

As mentioned, in theory nothing in /tmp should be critical. You could take
a shot at rm -rf inside /tmp.. (btw, why do you think /tmp is an issue?)

You can also remove the unwanted packages installed in your linux machines.
In ubuntu you can cleat the files in /partition and just notice from synaptic package manager all
debian packages wil be stored in /var/cache/apt/archives
so u can remove the debian packages by using the command rm -rf *.deb
now check ur disk space by using the command df -h

Filesystem Size Used Avail Use% Mounted on
/dev/sda10 8.7G 8.2G 3.9M 100% /
varrun 502M 164K 502M 1% /var/run
varlock 502M 4.0K 502M 1% /var/lock
udev 502M 120K 502M 1% /dev
devshm 502M 0 502M 0% /dev/shm
lrm 502M 19M 484M 4% /lib/modules/2.6.15-28-386/volatile
/dev/sda1 9.8G 8.8G 1002M 90% /media/sda1
/dev/sda5 8.9G 6.7G 2.3G 75% /media/sda5
/dev/sda7 4.0G 3.3G 524M 87% /media/sda7
/dev/sda8 956M 955M 0 100% /media/sda8
/dev/sda9 3.9G 2.4G 1.3G 66% /media/sda9

The terminal will display like this.now type exit in the terminal.Now ur machine will boot into the gnome mode.