Computer won't go past HP post screen?

I have an HP desktop that's about 1 yr old. When you turn it on it will not go past the HP post screen. If you try to enter bios it just says entering setup... and sits there forever. If I unplug the hard drive, however, I can enter bios and get to a screen that says boot device not found insert boot disk and press any key. If I put in a bootable CD it works. I am assuming that all of this means that the hard drive is broken. Also, if I plug in the hard drive to another computer (either via sata or sata to usb connector) it doesn't show up. Actually if I plug it into a sata port it causes that computer to stop at the post screen as well. Via usb, the drive just never shows up. Before I get a new hard drive, I just wanted to make sure that I'm not missing something. Is there anything else that could be causing this? I guess I don't understand why I can't even enter bios when the hard drive is plugged in.