Why doesn't the Enter key work?

Hi,

In FrameMaker 8 files in a particular project, I am having a problem with not being able to press Enter at the end of a to get to the next line.  I get the error, I: apiname in a blue bar at the bottom of the screen when I press Enter.

Do you have any idea how I can work around this so I can enter text on new lines?

Thanks,

Erin