The first Safecracker game (from 1997) was made to work on 100 MHz computers. The game played fine on older computers, at least up to 400 MHz, but had a problem on newer, faster computers -- the inventory scrolled past at super speed and you could only access the beginning and end of the inventory list. See the picture with the inventory list at
***Mobygames***. That inventory list was very long, and without scfix you could only access items at the very beginning and very end of the list. Hence you couldn't play the game.
Then someone wrote a program called scfix that fixed the problem, and Inferno wrote a Setup on how to play the game on XP
(Inferno's
***Safecracker Setup***)
which explained how scfix worked and what other tweaks were necessary. Scfix worked great back in the days when computers had single core processors that ran at around 1 GHz or so. But now that computers are so much faster, and use multiple-core processors, scfix is no longer sufficient. Computers are too fast even for scfix to allow you to play.
You might be able to run Safecracker inside a Virtual Machine, with the help of scfix and at least one PC slowdown program running inside the Virtual Machine. No guarantees though. The easiest way to run it is on an old computer (between 100 MHz and 400 MHz) with Windows 95 or 98 installed.
The Safecracker game that was made in 2006 is not a sequel and was not made by the same developers. This is the Safecracker most people are familiar with. It is not as long as the first one, but is better looking and has a better interface. It also runs on modern computers, though I don't know if it runs in Windows 7.
The Safecracker that was ported to Nintendo DS is the second one from 2006.