The Enter key is assigned to insert a Column Break not a paragraph return.
For a carriage return you need to press the Return key.
Some computers don't have a Num Pad and therefore the Enter Key is assigned to where the Return Key is.
If you go to Edit>Keyboard Shortcuts
Product Area: Type Menu
Insert Column Break - and remove the Num Enter value
then go to the Insert Paragraph Return
and remap it to the Enter Key.
Are you using the enter key with the number pad or with the alphabets?
Try using the enter/return key with the alphabets.
I really appreciate your help. I failed to mention I am using a notebook computer, and as such it was treating my one-and-only 'enter' key as a number pad enter. I have changed the keyboard shortcuts now, and it all works perfectly!
For other users having the same problem, when you assign your new shortcut, you need to select the context as 'text' before pressing 'assign'.