I updated my ubuntu server yesterday to 13.04 and instead of the login screen my kvn card said "signal out of range". However, I could login by entering my user and password blindly. I could only solve the problem by selecting an older kernel when entering grub during boot sequence. Furthermore, ubuntu also says to switch to the new release which is already running. I think I am using an intel graphic chip and I am not running any desktop on it. No errors appeared during the release upgrade. Maybe others also have this problem.

Welcome to Ubuntu 13.04 (GNU/Linux 3.5.0-30-generic x86_64)

* Documentation: https://help.ubuntu.com/

System information as of Wed May 22 10:46:54 CEST 2013

System load: 0.0 Users logged in: 0
Usage of /: 10.1% of 223.32GB IP address for em1:
Memory usage: 6% IP address for virbr0:
Swap usage: 0% IP address for tun0:
Processes: 85

Graph this data and manage this system at https://landscape.canonical.com/

0 packages can be updated.
0 updates are security updates.

New release '13.04' available.
Run 'do-release-upgrade' to upgrade to it.