Please check whether Googlebot and Bingbot are not crawling broken random URLs as it happend to me.
Something like:
[code]66.249.66.62 - - [06/Oct/2013:22:05:04 +0200] "GET /gallery/displayimage-1-8.htmlalbums/userpics/10001/albums/viaggio-newyork/most...
Something like:
[code]66.249.66.62 - - [06/Oct/2013:22:05:04 +0200] "GET /gallery/displayimage-1-8.htmlalbums/userpics/10001/albums/viaggio-newyork/most...