Why would URLs submitted in Google Webmaster Tools drop to 0? It's a small site, only like 20 pages, I submitted the XML sitemap and for about a week it said 20 URLs submitted. A day or so ago it indexed about 17 of the pages, but today when looking it not only says that 0 are indexed but also 0 have been submitted.
I did a site search on Google and found clearly that pages are indexed, is this just an error on Google Webmaster Tools?