There is an option known as "On Stop Rewind to Now Marker" which changes the default behavior of what happens when you press the Spacebar. If you deselect this setting, the behavior when using Spacebar by itself and CTRL + Spacebar will be inverted.

By default, when you press the Spacebar, your Now Time will rewind to the position it was at before pressing Play. If you hold CTRL and press the Spacebar, then the Now Time will stop at the position it is currently at.

In SONAR X1 and Music Creator 6, this behavior can be changed by going to the Options menu in the Track View and toggling "On Stop Rewind to Now Marker".

In older products, you can change this behavior under Options > Global > General by un-checking "On Stop Rewind to Now Marker".