Windows Registry Editor Version 5.00 [HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Rockstar Games\Grand Theft Auto IV] "InstallFolder"="C:\\Program Files\\Rockstar Games\\Grand Theft Auto IV"
Run the .reg file and confirm.
Note: Your old "Complete Edition" saves will not work with 1.0.7.0. You will need to start a new game or find a 1.0.7.0 save file online. 4. Install Essential Fixes downgrade gta iv to 1070
The easiest method is using a community-developed Downgrader Tool. Run the tool as an Administrator. Select your game folder. Choose as your target version. Windows Registry Editor Version 5