I'm using Xubuntu and upgraded to 13.10 as the system dialog suggested it. However, after rebooting and logging in (the Loginscreen still perfectly works), I only see a black Desktop with an invisible mouse cursor, and my taskbar on the bottom. The invisible mouse is still useable as onMouseOver Effects apply.
After searching through the internet for a solution (the Guest Login still perfectly works), it seemed like the ATI drivers may be the root of evil here and it had been suggested to remove all fglrx packages and continue with the open source driver.
After uninstalling fglrx and rebooting, I'm experiencing exactly the same issues as mentioned in this question: Unity doesn't load, no Launcher, no Dash appears
No Taskbar, no Mouse, just the plain Desktop Background. The problem at this point, however, is, that I use Xubuntu and xfce and none of the solutions of the mentioned thread was applicable for me so far as I don't have unity or compiz.