I currently run windows 7 32 bit. I downloaded ubuntu 12.10 iso from <http://www.ubuntu.com/> then I burned it to a dvd. I tried to install it and everything goes fine until I reach the option *install ubuntu alongside windows 7* then on clicking continue the DVD ejects itself and "please remove the installation source from the tray" appears on the screen, and again windows starts and the installation remains incomplete.

I then created a bootable USB and tried to install but again on the same option installation stops. I'm not an advanced user so the "try something else option" looks too complicated. I tried to use it but I dont know how to use this option. How can I install ubuntu? Is it that windows 7 is not allowing me to install ubuntu or is the problem something else?