Computer immediately boots into Startup Repair

Hi,

So, I have a computer that I have to give to someone. The problem is, that every time I boot the computer up, it shows "Starting Windows" for just 1 second and immediately boots into Startup Repair. Startup Repair then fails to fix the error, but from the info I got, it seems that the registry is corrupted.
The things I have done:

1. Copy new files from the DVD to the config folder - Nothing changed.
2. Check the HDD for problems. Seagate SeaTools - Passed the long and the short test.
3. Check the RAM - Memtest86+ v5.01 - no errors.
4. How I got the error: First, I tried to install SP1, but it rolled back. Second, then I installed the drivers for the computer and restarted every single time it asked. Tried SP1 again, but this time I got this issue.

System specs for that computer are after slashes (for every part).
Sorry for any grammar mistakes.
P.S. Can't access the CMD from anything (From Startup Repair, from DVD).

Hi Haexagon,
As the comp hasn't got SP1 on it, and your passing it on.
Why not clean install, dont forget to change Bios order to DVD as first boot option.

Roy

Hey, thanks for the suggestion!

I might do a clean install, but now gonna install Windows 10, because at one time, I had Windows 10 on that computer and it never did this kind of thing. But I remember Windows 7 doing that "system restore" thing. What could be the problem with Windows 7?

Hi Hexagon,
My GUESS lookin at those specs, its something to do with the Slave drive, W7 not picking it up properly.

Roy