I am using Ubuntu 12.10. I installed updates and graphics card driver. after that, i lost desktop.
this is screenshot. no unity, panel and others.
Driver = ATI Mobility Radeon HD 5430.
Driver Version v12.10
I have also ati radeon hd 5450 and after installing its driver I had the same problem as you. But I solved it after performing following command:
Hope it will help you. For more information you can read following resource here - ATI Raden Ubuntu Quantal Installation Guide .
A well known problem with ATI on 12.10 ! I had the same problem with ATI 75xx card but disabling ATI proprietary driver and enabling X.org solved the problem. Anyway, I found this blog post here see if that could help.
You can always try disabling the ATI driver and activate the good old X.Org driver in Software Sources >> Additional driver >> Use X.Org driver