I recently installed windows 7 on my pc and I have been unsuccessfully trying to install ubuntu 12.04 on it. I used to have dual boot system before both with windows and linux. I changed my hard drive from ide to ahci (default option) burned the ubuntu cd properly (not the .iso file) using the ubuntu 12.04 distribution I downloaded from the official site, set boot priority to cd/dvd but.. Nothing. It tries to boot from the cd, doesn't manage and turn to boot from the hard drive. I also tried wubi. I opened it through windows, got the window that asks me to choose "demo and installation" or "more on ubuntu" (something like that), I choose the first option, reboot manually my computer and it keeps returning on windows mode and doesn't boot from the cd.

What can I do? Thanks!