I have used Ubuntu for two days now when my Synaptics touchpad stopped working. It would still be able to click, but not move/tap. I then went to activate additional drivers as it told me I needed to do. After that, it said that in order for these drivers to take effect, I would need to restart my laptop, so I did. The problem is that, when I would boot into Ubuntu (I have dual boot; Windows 7 and Ubuntu), I would get the usual Ubuntu logo and the 5 dots, but then the screen would go black.
After asking an IT friend of mine who regularly uses Ubuntu, he believes I may have a bad xorg.conf file. He suggested I boot into single user mode and try a different user root. I am able to edit GRUB so as to boot into single user mode, but when I try to actually boot, all I get is a purple screen. No Ubuntu logo and no dots underneath. Mind you, I am pretty green when it comes to using Ubuntu and have been only using Google to troubleshoot.
If it helps, I have an HP Notebook G42 and it's about 3 years old.