I've got some issues with OpenGL and Direct3d. When I switch to either of them, my game slows down and speeds up randomly. With D3D, skybox textures get really messed up. I'm running Unreal with patch v224, and here are my laptop's system specs:

MS Windows XP Professional SP3
Genuine Intel CPU T2050 @ 1.60GHz, 1.0GB RAM, ATI Mobility Radeon X1400

I've tried several things already, but nothing has worked. I've been forced to use the default software rendering because that's the only thing that lets the game run smoothly.  

Thanks!