Blank kernel consoles

[osishkin]

Hi,

I'm using VirtualBox 4.2.12, with Xubuntu 13.04 (amd64) installed on it, and kernel 3.11.
I need to use kernel consoles, but cant use them. Switching to any of them (ctrl+alt+f1...f6) simply shows a blank screen with no cursor etc. I can return to graphical interface using ctrl_alt_f7. Any suggestion on what to do?

Thank you