the url for BTCguild needs updating. the www. is required or the site pitches an error page at you, rather than the expected JSON data, breaking the balance fetching.
Good catch. I'll put an update out today with these fixes.
adding "www." in a few places in servers.ini fixes the problem.
{ "name": "BTC Guild",
"host": "btcguild.com",
"url": "http://www.btcguild.com",
"port": 8332,
"balance_token_url": "http://www.btcguild.com/my_api.php",
"balance_host": "www.btcguild.com",
"balance_url": "/api.php?api_key=%s"
},