I installed Ubuntu (12.04) on my Acer Aspire 5734z and the back light stopped working. I have tried the fix by editing the grub file posted on here a couple of days ago but that hasn't fixed it. I have also looked for hardware drivers but that didn't get me anywhere. When I hook up an external monitor it works fine but I have been unsuccessful getting the laptop display to light up.
edit removed link
I found a fix here " http://crunchbanglinux.org/forums/post/66562/#p66562 " if anyone has a better fix than the one in that post, let me know.