An attempt was made to load a program with an in correct format..

When you have the following error:

C:\SC.Processing.Scheduler.Service>InstallUtil.exe SC.Process
ing.Scheduler.Service.exe
Microsoft (R) .NET Framework Installation utility Version 4.0.30319.1
Copyright (c) Microsoft Corporation. All rights reserved.

Exception occurred while initializing the installation:
System.BadImageFormatException: Could not load file or assembly 'file:///C:\SC.Processing.Scheduler.Service\SC.Processing.Scheduler.Service.e
xe' or one of its dependencies. An attempt was made to load a program with an in
correct format..

You'll probably have the invalid build of the installutil. Try switching between the versions in C:\Windows\Microsoft.NET\Framework\v4.0.30319 (x86) and C:\Windows\Microsoft.NET\Framework64\v4.0.30319 (x64).

Cheers & happy St. Patricks day,
Luuk