EDIT: I have since fixed the issue. I had to reseat the RAM in the machine itself.
Now, I need to know how I can boot back into Mac OS X. I can boot into Windows 8 as it's set as the default start-up disk.
Startup keyboard commands still don't work so I can't boot into OS X from there.
In Windows, there are no Bootcamp options to be found.
The question has been closed for the following reason "The question is answered, right answer was accepted" by DJ Scooby Doo Jun 17 '12 at 14:37
Which version of OSX have you got installed?
If its Lion then just use CMD + R to enter recovery mode.
answered Jun 17 '12 at 09:22
I'm assuming you unplugged the system, pressed the power button for 30 seconds to 2 minutes, plugged it back in and see what happens?
Usually that fixes the problem with other computers when they act up.
answered Jun 17 '12 at 13:50
DJ Scooby Doo