I think that the conflict was with remnants of Norton and not specifically with Ghost (a norton/symantec product) as the title of the topic implies, shadows of norton (a real pig to remove).
Sparrow later reports after uninstalling ghost and running regseeker clearing out norton/symantec entries he was able to reinstall ghost and no issues with avast.
So if you have never had norton antivirus installed and only ghost you shouldn't have any issues.