Nant.exe won’t run – Access is denied

When using Nant a while ago all was going well until I encountered an “Access is denied” message in DOS.

I tried running the executable again and was also presented with this very helpful message:

I did a bit of checking and then noticed that the filesize of the exe look a bit suspect.

I am not sure what caused this as it was working fine but copying the original exe back over this corrupt copy fixed the issue.
Hopefully this will help save you some time if you come across the same issue.