Try just pressing the Ctrl-Alt-F2 keys at the same time and see if you have a command line login prompt.If you do need to interrupt grub, you hit Esc when you first see the "Bootin... [by TrevorH]
I am new to Linux and trying out different distros. However, my laptop has ATI GPU (Asus N56D) due to which many distros didn't boot successfully. After having google'd I found that I need to set "NOMODSET" kernel parameter.
I could edit the grub command line (by pressing 'e' at the grub) but unable to boot after pressing Ctrl+X or F10.
When I click a user name on the login screen, the other ones disappear but the password prompt never shows up. It stays this way for a few seconds, then comes back to the original state with the list of users.