I installed 12.04 on my windows vista laptop. I wanted to make run Ubuntu and ditch windows. I selected to delete disk and install 12.04. It won't let boot 12.04 with out the install disk. When I turn on my laptop now it goes to a black screen with a blinking cursor. I have to power off then insert Ubuntu 12.04 cd as if it wants me to reinstall. I checked the drive and Ubuntu is there with some of my other saves as well. Can someone help me please?
I just had a problem that looks a lot like yours. Turns out the installer installed the boot loader on the USB key I was installing Ubuntu from. I re-installed it using advanced settings, setting the boot loader to install to sda1 instead of sdb1 and it worked fine after.
If you can boot into the LiveCD try doing a Boot Repair.