scriptCopy = game.ServerStorage.Infecter:Clone()
scriptCopy.Parent = headfoil
This takes place in the Infector script. Headfoil is a variable, describing the
hit.Parent:FindFirstChild("Head")
The script's ideal function is to give an infected player the ability to infect another.
****GAME: RED SICKNESS: A game like The Roblox Plague

2 comments
I think you need to give us more code before we can help.
If it crashes it might be due to some loop in your code. I recommend using debounce and print statements to find the problem. From what I see though, there's no way to identify where the problem is. More code is required.