Recently, I came across a Dell laptop, Studio 1555.
It came loaded with Windows 7, nice machine, BUT, my client needed Windows XP, for some DOS Programs to work on it. I checked online to see if Dell provided XP Drivers for it, and decided to downgrade it.
When I inserted my Dell Win XP, CD, it errord out with System halted error. I decided to look at BIOS, and maybe find something to fix the issue.
I changed the system drive to IDE from SATA
And that fixed the problem, and I now have windows Xp on Dell Studio 1555