boot - After kernel update, stuck on purple screen but old kernel still works

As the title says, the new kernel doesn't work. I am on Ubuntu 12.10.

I had 3.0.39 or something like that, and when I updated to 3.0.40, it just gave me a purple screen. However, with GRUB Customizer, I set my default boot entry to the old kernel and it works fine.

So my questions are:

1. How can I get my new kernel to work? And if not,


2. How can I delete the new kernel and make Ubuntu just boot to the old kernel?


3. And is it safe to remove the new kernel?

Thanks