Urgent hard drive issue

Hi guys, new to the forum - hoping you can help. I'll try and explain the issue in as much detail as I can without sounding confusing, if you need any further information then let me know.

I've just purchased a new hard drive as my current hard disk only has a rather pathetic 152GB of space (this was hastily installed a while ago as a stop gap). What I intended to do was install and use my new 1TB HDD as the main drive (which I would boot Win7 off) and keep the other drive connected purely as storage.

I decided to install Windows 7 as a clean install on the new hard drive (whilst the old one was still connected fyi) and it is all operational, however, the problem is as following:

- The new hard drive will not boot Windows 7 independently, the old hard drive still needs to be connected. This means I am unable to format the old drive as it is the active and system partition.

Without the old hard drive, it will not boot at all. Asks for a system disk. (DISK BOOT FAILURE)

- I have tried booting with the system repair disk but it just goes to a black screen now.

See screenshot below:



I've also found that my computer is shutting off at random intervals since I have tried repairing the new hard drive bootup - I'm concerned that I'll lose my data hence me posting a topic here.

If you can make heads or tails of my issue then I would really appreciate some help on how I can fix this. Thanks!