Black screen on startup

[ChaCol]

When I start up the computer it goes to this black screen with a white blinking _ and after that is up for about 10 seconds, it goes to the screen that allows you to select Safe Mode, Last Known Good Configuration, and Start Windows Normally. If you click on any of them it just freezes and nothing happens. If you wait until the timer runs out, it just goes on to a black screen and does nothing. I can't enter my BIOS to run from the CD drive to reinstall the OS.. so what do I do?