From the website of most of the major distros, from distrowatch, and I think here at LQ.
Most major distros now come in this form.

You can simply click on the "Download Linux" link in this site's Main Menu and the click on the link to download knoppix. Did you try accessing a virtual terminal as suggested in post #14. You should be able to log in and edit your files in vim, emacs, or your favorite console text editor.

distrowatch.com

I generally get a Knoppix or Gentoo liveCD (or live DVD). One or the other works (or not) on my laptop(s). Sometimes even both. There's even versions that support booting from a flash (thumb/usb) drive.

Boot the liveCD and you're IN linux. Run linux from there and be happy, or use that linux to mount the partition and edit the files that trouble you on your normal linux. If it's not something that you've used extensively, you might even consider a reinstall of linux on the offending machine. Just one of many options.