Laptop only boots from CD/DVD with HD removed

[mjspam]

Suddenly, my laptop started to have problems booting. When I press the power button, it starts to power up, but quits after a few seconds (3-5). I can hear the drvies/fans start to spin up, and then it just powers off. The initial screen displays for about .5 seconds -too fast to read any messages.
I have it configured to boot from a CD/DVD, so I tried that, but it didn't work either - UNTIL - I removed the hard drive itself. Now I can boot fine from a bootable CD (typically a LINUX Live CD). I even replaced the HD with a new one, but its doing the same thing with the new drive.
Any help would be greatly appreciated. The laptop is an older HP zt1000, long since out of warrantee. Thanks.

 

[TypeX45]

Can you at least hit f8 and see the menu where you can choose safe mode or does it even allow you to get into the bios.

 

[mjspam]

No access to bios

I can't even get that far. I assumed it was a hard drive problem, since it boots okay from the CD drive when the hard drive is not physically in the unit. (Its always set to check the CD first.)

 

[mjspam]

Okay - now I can't get it to boot at all.

With or without the hard drive in. I've removed the battery - still won't boot. Each time it fails, I have to momentarily disconect the power adapter, or else it won't even start to power up.