Minimum System Requirements for Halo..
Operating System: Microsoft Windows 98, Microsoft Windows Second Edition, Microsoft Windows Millennium Edition (Me), Microsoft Windows 2000, or Microsoft Windows XP.
Computer/Processor: 733 megahertz (MHz) processor.
DirectX: DirectX® 9.0 or later. (DirectX 9.0b is installed by Halo.)
Memory: 128 megabytes (MB) of RAM.
Hard Disk: 1.2 gigabytes (GB) of free hard disk space.
Video card: 32 MB with 3D Transform and Lighting capable.
CD: 8X.
Sound: Sound card, speakers, or headphones with multiplayer play.
*56.6 Kilobytes per second (KBps) modem or 10 MB network adapter. Multiplayer servers require broadband to run a server.
*Additionally, you must have an Internet Service provider (ISP) or a Local Area Network (LAN), if you want to play multi-player games.
Highlighted text...is most likely the cause. Surprised you can even run it. You can try another set of drivers...or turn off all the other features to see if it helps the issue.