Could any of you test again with: OffscreenRenderingMode=fbo turned on?
fbos are broken with half life 2. It is broken because it uses a different depth stencil buffer size than the color buffer size.
I just turned that off (so it defaulted to backbuffer), and the problem actually went away. I had this turned on because it seemed to with problems with other games though. Which offscreenrenderingmode should be giving the best performance/compatibility?
For half-life 2 I'd suggest back buffer for now because nowadays it renders on AUX buffers which is faster than the context switch for pbuffers. Once fbos work with that game they should be used.