I haven’t actually enabled the All RSS Feed.In the Global RSS Settings in SP, there was this option
Replacement external RSS URL for all RSS:
Default: http://www.aristotleprep.com/forums/rss/
So I just used the URL above in the widget and it was working properly. Should I enable the All RSS feed ?
I researched on the error and came across this link. Seems like this kind of error appears when there is some extra space outside of <? ?>
http://www.pagalz.com/blog/2009/08/xml-parsing-error-xml-declaration-not-at-start-of-external-entity-%E2%80%A6-line-number-2-column-1/
What I don’t understand is that why would this error creep up all of a sudden because I did not make any changes to the files apart from what you suggested.