I installed Ubuntu on a drive with Windows 2000. When the PC boots you have the choice to select Windows or Ubuntu. I choose Ubuntu and the start up screen pops up and the dots at the bottom change color and the hard drive light on the PC is flashing. After about 1 minute the dots stop moving as well as the hard drive. It then freezes and the PC has to be restarted.
At the boot menu you mentioned earlier, try the Recovery Mode option for Ubuntu. This should display more diagnostic information, and can help determine the problem.