If you are experiencing errors when installing the Title Update through the LIVE service, please download the Title Update manually from the link below and run the Installer once it is saved to your hard drive:
Title Updates and Patch Notes for GTA IV PC
If you receive an error from the downloaded version of the Title Update Installer, please try to run the Installer again.
If the error still persists, please click 'Show Details' and find which file has failed. When you have the name of the file(s), please contact customer support.