What is one of the main problems that can occur when implementing a large number of new systems within an organization?

Trying to conduct business as usual while still training, learning, and migrating to a new system, is one of the main problems that can occur when implementing a large number of new systems within an organization. Linking up together problems that go hand in hand with a lengthy implementation process and the company conducting business as usual, this always becomes a very big issue. This practice of employees attending to their daily tasks of their main job and contributing to the software project at the same time can be detrimental and can cause software implementation to take much longer.