Kernel Panic Error on Mac OS X Mountain Lion

I'm running Mac OS X Mountain Lion. I am getting a kernel panic error when I restarted my computer. As far as I remember, I shut it down properly the last time I used it without any issues. But when I opened it today, it has an error. And then when it restarted, the same error will just showed up. How can I fix this?

You shut down your computer because of a problem.
If you want to open the applications that were open when you shut down, click Open.
If you do nothing, the computer will continue the login in 56 seconds.
Cancel    Open
