Task Splitting is normally switched on in Microsoft project and users end up with splits at the start of a task which is quite difficult to sort out.

What is Splitting?

Splitting a task puts one or more breaks in a Task, leaving:

1. The Duration value unchanged with a Fixed Units task but the elapsed duration is increased
2. The Duration value changed with a Fixed Duration task to equal the elapsed duration, and
3. Resources assigned to a split task are not assigned work during the splits