Encoding/Decoding Problem – Who's to blame? WordPress, PHP or my SQL?

I have uploaded an image from my PC via the media uploader with the following filename: test-2×2-klj-jersey-2010.jpg
(I’m using the WP User Avatar plugin by flippercode)

I extract the image url from the ‘guid’ field on the posts table and it gives me:
http://mysite.com/wp-content/uploads/2014/09/test-2×2-klj-jersey-2010.jpg which gives me a 404 because the “x” in the filename (2×2) has been retrieved as a small check mark. If I change this back to an “x” in my address bar, the file is there.

I’m not sure if the check mark will appear in the mysite.com url example above but if you go to
http://liveauctionrooms.com/view-auction-room-details/
you will hopefully see what is happening

Does anyone have any idea of what’s to blame?

Thanks in anticipation
Kevin