One of the other things to look into are the other services that can't be started I don't know if there is some dependency thing going on here that the avast sandbox also requires.
Whilst you say you have snxhk.dll in that location that doesn't mean that it is running, so I don't know if using the rundll32 command - rundll32.exe snxhk.dll to start it. I don't believe you need to enter any paths.
