my original post with this problem got jumped on by admin because i didnt put backticks round the code and added it to someone elses post, hence the lack of the code at the start of this post.
The firefox caching was causing even normal rss feed from em to look wrong but clearing all of the caching and restarting firefox between looking proved it to be OK
Dont even try to use opera to look at rss feeds.
The problem was with my code (would you believe it!)
add_filter( ’em_events_build_sql_conditions’, ‘my_em_scope_conditions’,1,2);
is missing from the top.
so the option appears in the rss setting page but doesnt get implemented and dumps all events into the rss feed.