Thanks for your reply.
It would appear to be the theme. I switched to the default theme and back again and for a brief period the RSS feed worked.
However, a few minutes after switching back to the current theme it stopped working again.
I am using the theme Yashfa 1.7 by Nurudin Jauhari which I would prefer to keep.
Does anyone know how to fix this problem within this theme?
Thanks again.