I recently installed 12.04 on my desktop and upgraded to 12.10.
Since then the screen constantly goes blank every 5-8 seconds. It never did this in 12.04. I have the same issues when I have tried to install 12.10 from a live CD.
There is a high probability for this being a driver-related issue.
If you are using the proprietary driver try to upgrade or if this does not help uninstall it.
If you are not, try installing the proprietary driver using: