This won't completely solve the problem, but it'll get you to a terminal:
1. At the grub menu hit the spacebar
2. Highlight one of the kernels, press 'a'
3. You should be able to edit the line of text that is displayed, add a space and a 3 to the end of that line
4. Press enter.
This boots you into runlevel 3, which is text based, you should have a text login now, and you can type startx to open gnome/kde