After a PR update, my site went up from PR-3 to PR-5, but my keywords and site index page drop off from the google indexing. even by giving site: operator and either giving a site address, the site is not appearing in the search results. Also not found for any keyword. Only few site pages are indexed in the google, but the index page disappeared. In addition to this, sometimes when I give "site:" operator it returns index page but when I search it again, it drops off... could you please tell me what is going on with my site. Is this kinda penalization, and if so then why Google gives me PR-5.