Today, I decided for the first time in a long time, I would load up the first Grand Theft Auto and play a bit of it. I loaded it up and I played for about an hour before I had to work on something. I came back about two hours later and the game refused to load, crashing me back out to the desktop. I did some searching and I found the culprit. It seems Grand Theft Auto makes a change to a file every time it launches. From what I can tell, the game will continue to work fine on x86 machines, however, on x64 the game just crashes with this change. I have created a small little program that changes this file back to a working version for x64 machines and then launches the game. It works with both the free Rockstar version and the Steam version of the game.

Site: Grand Theft Auto I Launcher