RSS Feed Issue: Chrome, Firefox and W3 Validator

Dear all,

If I use Firefox and read my /feed it shows me a clean RSS Feed and no problems.

If I use Chrome for the same feed path I receive this error:

error on line 173 at column 1715: Opening and ending tag mismatch: encoded line 0 and script

then I see a list of html code instead of a formatted text in Rss style.

I used the w3c RSS Validator (http://validator.w3.org/feed/) and I typed in the RSS Feed link of my Wb which is http://www.tuttoirlanda.com/feed
and I received several errors such as

This feed does not validate. XML parsing error: <unknown>:170:1707: mismatched tag”

and other errors.

I use swift theme with Seo Yoast, W3 Total Cache.

Appreciate any feedback.
Thanks in advance
Donald