Thank you for your help.
Tried both of your suggestions, but still the same problem.
I tried loading the l4d2.exe from the steam folder rather than running it through steam, and put a log on it. Then I tried through steam to get a log. The results are a bit over my head, and I'm not sure what to post.
When I ran the exe directly, I got an error:
"The command "/Users/XXX/Library/Application Support/CrossOver Games/Bottles/steam/drive_c/Program Files/Steam/steamapps/common/left 4 dead 2/left4dead2.exe" returned 100.
StdOut:
StdErr:"
The Log showed a whole long list of "fixme". It also had this line: "GL_INVALID_FRAMEBUFFER_OPERATION (0x506) from glClear @ directx.c / 803" but I'm not sure if that's where the error is. I'll go back and try the dxlevel again. I also got a lot of "d3d:debug_d3dformat Unrecognized" followed by various numbers and "WINED3DFORMAT!".
When I ran through steam, I got pretty much the same messages.
UPDATE:
I tried the VideoMemorySize 'performance tweak' in the tips and tricks ... and now Half-Life is dead too. Portal will still load but the entire half-life series is down.
I'm worried I'm going to have to wait for Steam on Mac, because it looks like Steam on Crossover is messed up now.
UPDATE:
On the off-chance that something is fundamentally wrong with my installation of steam, I decided to be radical and reinstall. I'll let you know how it goes ... though at this point I might simply wait for Steam to come out on Mac and use crossover for my Non-Steam apps.
UPDATE:
Deleted steam and reinstalled. L4D2 still can't get past the opening movie. Didn't try the others. Will likely give up on steam and wait for it to come out on mac.