[ubuntu] Can't install on Dell optiplex 760

I am trying to install Ubuntu 12.04 LTS on my Dell Optiplex 760 but it always gets stuck on the loading screen. For some reason my computer does not shows me the BIOS or the Dell logo at startup so I cant see the Ubuntu menu when you boot from the CD. It goes straight to the Ubuntu name with the loading dots and at some point it gets stuck. I have tried using a CD and flash drive to boot from and I get the same problems. I know the cd and the USB work because I tested it on other computers sop I don' t know why it always gets stuck.

I am running Windows 8 and tried using the Windows installer but it gives me an error so I cant install it either.