That is harmless warning caused by a private QtNetwork method being called more than once. The method simply returns in this case, so there is no harm done. Your problem is probably caused by some error in parsing the RSS feed. If you could list the feeds you have tried, I will test them on my device.
http://bash.org.pl/rss http://android.com.pl/feed/ http://talk.maemo.org/external.php?type=RSS2