RSS Feed Has Stopped Working

My RSS feed – usatips4brits.co.uk/feed has stopped working, I recently installed a new theme and wonder if that is causing the problem or not??

Here is a copy of the error message:-

This page contains the following errors:

error on line 122 at column 25: Input is not proper UTF-8, indicate encoding !
Bytes: 0x03 0x44 0x6F 0x65
Below is a rendering of the page up to the first error.

UsaTips4Brits http://usatips4brits.co.uk Free Orlando Disney World Guide For Brits Sun, 01 Sep 2013 08:53:33 +0000 en-US hourly 1 http://wordpress.org/?v=3.6 Brit Guide Orlando 2014 – Pre Order Now http://usatips4brits.co.uk/archives/1349 http://usatips4brits.co.uk/archives/1349#comments Sun, 01 Sep 2013 08:53:33 +0000 jimihat69 http://usatips4brits.co.uk/?p=1349 http://usatips4brits.co.uk/archives/1349/feed 0 Theme Park of the Gods??? http://usatips4brits.co.uk/archives/1347 http://usatips4brits.co.uk/archives/1347#comments Sat, 31 Aug 2013 15:56:25 +0000 jimihat69 http://usatips4brits.co.uk/?p=1347 http://usatips4brits.co.uk/archives/1347/feed 0 20% Off Travel Insurance http://usatips4brits.co.uk/archives/1273 http://usatips4brits.co.uk/archives/1273#comments Thu, 22 Aug 2013 14:59:51 +0000 jimihat69 http://usatips4brits.co.uk/?p=1273 http://usatips4brits.co.uk/archives/1273/feed 0 Useful Information for Disabled Holidaymakers http://usatips4brits.co.uk/archives/1263 http://usatips4brits.co.uk/archives/1263#comments Wed, 21 Aug 2013 21:35:35 +0000 jimihat69 http://usatips4brits.co.uk/?p=1263 http://usatips4brits.co.uk/archives/1263/feed 0 WIN a £5,000 Orlando Family Holiday!!! http://usatips4brits.co.uk/archives/1207 http://usatips4brits.co.uk/archives/1207#comments Tue, 20 Aug 2013 10:29:50 +0000 jimihat69 http://usatips4brits.co.uk/?p=1207

PLEASE HELP!