This is most likely due to a javascript issue in the rss item or the feed. You should try closing Eluma, then turn off script debugging in Internet Explorer, then restart Eluma. At that point you should not get any Debug error notifications and you can remove the offending feed.
To turn off script debugging in Internet Explorer, choose Tools->Internet Options and the choose the Advanced tab.
Eluma uses Internet Explorer to show content even if you use Firefox or another browser as your default browser.