I want to install Ubuntu 12.04 alongside windows 7. I downloaded Ubuntu and burned it in DVD, but when I tried to install it (I used both Try Ubuntu and Install Ubuntu options.), only purple screen with Ubuntu logo comes and nothing happens. Note:1.The Downloaded Ubuntu works fine in virtual box. If something goes wrong, I don't have windows 7 DVD to repair the loader problems.
Do you have uefi-bios ?!
Here is explained the most about uefi-bios.
In bios-settings (mostly to get there with key 'F2' - to see which key - look at booting of BIOS) ...
you should disable uefi-bios and enable efi-bios.
Probably, you have not burnt iso image properly. Or it might be a problem with your DVD Drive. You can check the DVD on another PC.