Here's the steps I witnessed: the BIOS steps clear just fine, GRUB loads up and defaults into Ubuntu after a countdown (I dual boot), the Ubuntu progress meter behaves normally, then it transitions to a black screen with a residual [OK] at the top of the screen (something left over from the splash and quiet boot message suppression) AND a functioning mouse cursor. Really odd IMO. I'm pretty sure the OS is functioning just fine at this point, but something isn't graphically working correctly.
Here's the fix I tried with success:
- While at the blank screen with the mouse cursor, hit Ctrl+Alt+F1. This should bring up a terminal.
- Log in with the credentials you set at install
- Type: sudo apt-get update
- Type: sudo apt-get upgrade (given this few of days since the release, I saw a few updates for Compiz)
- Reboot. Type: sudo shutdown -r now
- Problem should be fixed
I suspect it had something to do with LightDM and Compiz not behaving correctly, and the Compiz updates fixed the problem. Good luck!