The patch addressess the following issues:

- Inability of users to map the mouse buttons.
- Inability of users to map the "center camera" button.
- Some occasional crash fixes.
- Graphics card stability:
+ A change to re-enable use of some graphics card features on ATI hardware, with their latest drivers.
+ Progress has been made towards addressing stalling on GeForce 6/7 series hardware.
- Fixed compatibility issues with certain Realtek sound drivers which could cause crashes.
- Autosaves now made for each chapter. Number of save slots is increased to accommodate these.
- Bug with ramp not raising in Xibalba.
- Fixed black screen deadlock when skipping doppelganger cinematic.
- Issue with door lever at Kraken room entrance.
- Occasional control issue during headshot move.
- Fixed an occasional problem when entering a save game filename.
- Some PDA fixes.
- Some cinematic subtitle fixes.
- DISC version only supported.

http://www.tombraiderchronicles.com/underworld/patches_pc.html