i am facing similar prob....I am not getting a answer to my prob. Actually, i am analysing a sharp increase and decrease in my indexed pages. one day it was 9840 pages and the very next day it fall down to 3450. Also, that these days my website are goin many changes. Within 2 months my company has launched 3rd time after revamping the complete site. also we happen to  see many crawler issues in the new and old indexed pages. Kindly, help me with this technial issue as it is affecting my indexed pages big time with sharp fltuicatuon in the indexed pages.