A sampling of the client crashes shows that its crashing in shaderapi.dll from d3d9.dll. It also crashed in serverbrowser.dll (steam), vphysics.dll, filesystem_steam.dll.....
Basically he needs to completely wipe steam from his comp and reinstall it. He also needs to upgrade his video card drivers (which is why its crashing d3d9.dll imo) and potentially reinstall windows if all else fails.
The server crashes are all in engine.dll and kernel32.dll. Indicates memory corruption and/or a valve crash. Suggest you install srcds files.
It seemed like a lot of the second client's crashes were physics related and ragdoll related. Does your server run any plugins or customizations that add ragdolls or other kinda crazy things? That might be why the clients are crashing, because whatever plugin you are using is corrupting the entity and/or models of the associated ragdolls.
In other words: NONE of these are caused by GE:S
P.S. - When I say "upgrade" video card drivers I mean completely uninstall the existing ones, RESTART, Install the latest version, RESTART.