Comment 7 for bug 519358

G-Hattinger: I have exactly the same problem with my Acer Travelmate 243XC, however I don't believe that the two problems you have are related, i.e. the GRUB errors you are getting are NOT what is stopping your OS working; my machine boots the OS OK with those errors.

What I did to work round the black screen problem (which I assume is a Kernel bug stopping the graphics drivers for our laptops working, but that's just a guess) was to pass the string 'xforcevesa' to the kernel on boot-up. The easiest way to do this is when you first install Ubuntu (from the main menu press F6 and add 'xforcevesa' to the end of the line, then ENTER to boot.)

If the OS is already installed then you need to hold down SHIFT when GRUB loads, then you can press E to edit the default menu option, again by adding 'xforcevesa' in the appropriate place. Then, you should be able to log in where you can configure GRUB permanently to do this. Sadly, after searching extensively online, I still have no idea whatsoever how to do this, which is why I ended up reinstalling. (When you enter new options from the CD menu, it seems to remember them after installation.)

This should at least get you up and running but you'll have no 3D.