Ok guys, I'm lost and i hope you can help me.

Yesterday i fell asleep while my laptop was still on. when i woke up this morning i stared at a black screen. I tried to wake it up but nothing happened so i just turned it off.

But when i turn it on again i get this after the login screen:
Xsession: Warning" Unable to write to /tmp; X session may exist with an error

After a few minutes i get the message, that my temp directory id full.

Now the problem is, that i cannot even login in console mode!! i tried the "console login" mode from the login window, i tried switching the console with ctrl+Alt+F1, i even tried to start in recovery mode. But all i get is a blank screen with a blinking cursor in the middle, but i can't write anything!

So, does anyone have any idea how to solve this problem??

I would use a live CD to delete some stuff from your tmp folder. You know how to mount partitions from a live CD environment?

yeah! I forgot to mention: I already tried that too. I booted a live cd and emptied the /tmp folder. I still get the same error!

Hmmm, curious. A couple more idea's you've probly already tried -

Do you have a 'backup' kernel installed? You could edit grub boot line to try to boot that one if you do.

You could edit /etc/inittab from live CD environ and boot into a different runlvel. I can't remember what ubutnu uses for single-user mode - runlevel 2?