[ubuntu] Cannot change resolution on Ubuntu 13.04 Desktop with VMware tools

Hi,

I installed a new linux guest in my VMWare Vsphere 5.1 enviroment.
This guest is an Ubuntu 13.04 Desktop.

After the installation of VMWare tools I wanted to change the resolution because now it is 800x600. I cannot change the resolution cause then the system hangs.
Except when I change it to 1024x768 it works. If I change it into a higher resolution it also hangs if i apply the resolution. VMWare tools should normally manage the resolution.. What is wrong here?
The display is displayed as "Unknown" under the display menu in Ubuntu.

Kr,

Joeri