I've been using this desktop for a few years with ubuntu and had zero problems.

I tried plugging a blank 3TB disc into the USB and starting.

The boot immediately halts after leaving the bios options screen, displaying nothing but a flashing _, a few seconds later, the monitor goes dead and displays 'no signal'. There is no drive activity.

I tried unplugging the 3TB drive and power cycling, the problem remains.

I tried booting from the LiveCD and it comes up to the OS fine.

I can see the internal drive when I get to the OS, and all the data on it. If I look in GParted, I still have SDA1 there, with file system ext4 marked as boot and with 180gb on it. And SDA2, extended, and SDA5 linux-swap. But I now get a warning of bad sectors when the LiveCD boots to the OS.

I shut it down and stick Hiren's BootCD in, then run the bad sector / repair tool. It finishes and reports about 100 bad sectors have been corrected towards the end of the disc.

Personally, I am skeptical it's bad sectors and suspect that's a bug that's already been reported. It also seems odd that it occurred at exactly the moment I tried the 3TB disc. I've never seen any such warnings before.

This is a single OS install.

What's annoying is the complete lack of any error messages, or any information, to help determine what's going wrong. It's literally straight out of the bios, freeze, video signal disappears, drives stop. If I press the power button, it's also got no delay on it. Which is bios controlled. Yet it is still booting with the LiveCD.

I've tried leaving it for an hour and it'll still be sat there.

I could really use some help, as I'm not getting anywhere.

Thanks!

Did you try the option in the LiveCD menu to boot from the internal HDD?

Yup, same problem. As soon as I tap enter, the monitor looses the signal and it'll not go any further.

The fact it'll boot with the LiveCD means the motherboard and bios must be okay.

Since I can even see the drive and it's contents, and that it's partitioned correctly, I can only guess this is something to do with the recognition of the internal drive as the bootable; it is marked as such in GParted.

But then, why do I completely loose my video signal rather than getting a disk error?

You are almost giving enough information. Assuming that you do not have anything but Linux on your box it sounds like your mbr is screwed for some reason. This is easy to fix and doesn't take long. I would do that if I were you.

Use these directions from your Live CD.
https://help.ubuntu.com/community/Grub2
Just go down the menu and find number 12 (reinstalling).

Personally I think those directions are a little silly and complex but that is the way Ubuntu likes it. Should work fine. Do it and reboot and see if it is fixed.

If not reboot to the Live CD and run this script and post the results that will be on the Desktop of the live session here.
http://bootinfoscript.sourceforge.net/

1 members found this post helpful.

Runs BootCD, runs boot repair tool. Get's error, GRUB does not exist. Worries.

Shuts down, removing disc. Restarts. Monitor goes out, no signal appears. Worries more. Monitor TURNS off! But drive is clicking... oooooo tense....

LOGIN APPEARS!

Oh praise the widget, an internet kiss is yours! Thanks, that was really helpful.

Sounds good, have FUN.