Yesterday afternoon my computer screen, in the middle of just having mozilla firefox open(not downloading anYthing), turned blue and had the following error message:

A problem has been detected and windows has been shut down to prevent damage to your computerif this is the first time you've seen this stop error screen. restart your computer. if this screen appears again, follow these steps:
check to be sure you have adequate disk space. if a driver is identified in the stop mesage, disable the driver or check with the manufacturer for driver updates.try changing video adapters.
check with your hardware vendor for any BIOS updates. Disable BIOS memory options such as caching or shadowing. If you need to use safe mode to remove or disablecomponents, restart your computer, press f8 to select advanced startup options, and then select safe mode.
technical information:
stop : 0x0000007E (0xC0000005, 0x8AC6B367, 0xBA4CABA4, 0xBA4CA8A0)

after multiple attempts at trying to startup in various settings, including safe mode, my friend recommend I try knoppix because he successfully retrieved files this way. So on a second laptop we burnt knoppix to dvd and ran on my laptop (dell precision m6300 ) and everything showed up fine, including a newly attached external hd, but when I went to click my own hd, the following message came up:

Unable to mount device
error: org.freedesktop.Hal.Device.Volume.UnknownFailure

Any advice on further steps to take to access my hard drive would be appreciated. I have no idea how this happened in the first place, I was not running any updates or installs or anything.

Thank you so much!