Rockstar Games has today released a patch for the PC version of Grand Theft Auto IV which fixes a few known issues.

Updated automatically via Steam the update includes:

Graphics
* Interior Lights for ATI 1900 series cards
o All light sources appear for users with 1900 series ATI cards. (ie. Pool Mini Game)
o ALT-TAB fixed

* Graphics Settings
o Added menu option "OFF" for Reflection quality
o Added menu option "OFF" for Shadow quality
* Scrolling signboards
o Activate missing scrolling signboard text (ie. highway signs, Star Junction, Clock Tower Sign)

Performance
* Physics optimizations to improve situations with heavy physics calculations (ie. 32 player races)
* Graphical Performance Optimizations

Multiplayer
* NAT Type detection
o Detect if user has a "strict" NAT and displays message for user
* Voice chat is received even if your microphone is turned off

Controls
* Keyboard / Mouse
o Remapping restrictions removed
o Allow Enter, Backspace, and Arrow keys to be remapped by user
o Allow multiple mouse buttons to be mapped
* Enable/Disable DirectInput in Menu
o Users can now activate/deactivate Direct Input devices from "Controls" menu
o If commandline "-usedirectinput" is active, it will override pause menu setting
* Use 2 direct input devices simultaneously (ie. Wheel and Gamepad)
o Users can now use 2 different controllers at once, including 1 XInput and 1 Direct Input device
* Added more Direct Input / XInput device support
o Saitek P380/P480/P580/P990
o Saitek PS1000/PS2700/P3200/P3600
o Gravis Eliminator Shock gamepad

Security
* Detect modified files and prevent users from entering multiplayer if found
o Game will prompt with a message after blocking user with modified data files from entering multiplayer
o Should prevent multiplayer access from cell phone and GFWL join in progress
* Detect modified / non-original game launcher
o Prevent game from Launching if modifed/non-original game launcher is found