Rockstar have patched the PC version of Grand Theft Auto IV, bringing this sandbox game to v1.0.2.0.

You can get this update from GP Downloads (32MB). Changelog is as follows;

Graphics Menu:
Added "Water Quality", "Shadow Quality" and "Reflection Resolution" sliders in graphics menu.
Added "Definition" and "VSync" toggles in graphics menu.
Rendering optimizations.
VSync optimizations.
Nvidia 7000 series
Mirrors fixed

Direct input device support is now disabled by default and can only be enabled with the commandline: "-usedirectinput"
Supported Controllers:
Logitech Dual Action
Logitech RumblePad 2
Logitech Cordless RumblePad 2
Saitek P2500
Supported Wheels:
Note: Controls are unmapped, user must map controls using Manufacturer's mapping software.
Logitech G25 Racing Wheel
Logitech Wingman Formula GP Wheel
Logitech MOMO Racing
MOMO Force
Driving Force Pro
Driving Force
Formula Force
Added Commandline "-notimefix" which will help some users who are experiencing the fast/slow gameplay issue after patch 1 was applied.
Fixed a bug that caused some users to experience endless looping audio effects after Patch 1 was applied.
Benchmark was disabling sounds after Patch 1 was applied, this is now fixed.

Unable to load game fixed - For some users, a DOS window would open and close immediately upon Game Launch, GTA IV would never launch.
Hang on Initial Game Loading Screen fixed - Some users experienced Character Art Loading screens in an endless loop.
Certain causes of the RESC10 error have been fixed (Alt-Tab, change resolution). If you experience an RESC10 error, you must restart.
Certain Instances of the "GRAND THEFT AUTO IV has encountered a problem and needs to close" error have been fixed.

Naming clips is now mandatory on Export

Legitimate players being kicked from Multiplayer matches has been fixed.

Wireless 360 controllers not functioning - Triggers were full on/off, fixed.
In the Options menu accessed from the Title Screen a “Game” section has been added with the ability to turn Clip capture on/off. [/quote]