Honestly, it may be more Apple to blame with the Snow Leopard ATI driver issues...
I didn't start using CrossOver until late last year. Left 4 Dead worked absolutely great in 10.6.1 and earlier on my 2600HD iMac and 8.0.0, it was unable to work on my X1600 iMac at that time. When 10.6.2 came out, the 2600HD also stopped working. It was the black screen issue where all you could see was the text. This is exactly what was already occurring with the X1600.
I cannot remember which version of 8.1.X fixed the issue with ATI cards on Snow Leopard to get them to run at all (most likely it was 8.1.0). Left 4 Dead and Left 4 Dead 2 ran like a champ on both systems with no notable crashes. The crashes did not get this frequent until the 8.1.4 update. Unfortunately, that update is required to run Left 4 Dead 2, so it would be a double-edged sword scenario to downgrade. I've experienced a rare crash or two with Left 4 Dead 2, but it appears to be more stable than the original at this point. TF2 runs without issue. I play Left 4 Dead online more because it is still all a lot of friends of mine own (they didn't pick up L4D2 yet).
I have tried most if not all recommended toggles and suggestions. All I can figure is that this is a hard crash with the ATI Driver. I chased my tail in a lot of other directions, but it truly appears that it dumps when trying to cache/uncache effects and textures. The crash occurs when first entering a map, when changing to the next map (in the same campaign), when a molotov is thrown and pretty much any time a lot is going on on-screen. These issues now affect both machines when at first it only really seemed to affect the 2600HD - the best of the two.
One thing funny that I've noticed is that I have seen a lot more aimbot-using a...hats lately. I can now tell when someone is using a hack as when the map first loads I am missing textures (ground missing, general corruption). After leaving and then re-entering (which corrects the missing-textures and corruption), I noticed that the same person kept head-shotting the infected team as soon as they spawned. I'm usually a hack doubter, but I got a pretty good demo this time and noticed that this was common with the other times it occurred as well. It may be a very strange coincidence.
I am not angry with the CrossOver team, I am just a bit frustrated that I didn't hear of any tests with ATI cards. No one else using a Mac appears to have reported the problem, but maybe everyone has moved on to Left 4 Dead 2.
Maybe I am the only one...