Many pages dropped from index

[lici]

Since the last index update about 80% of my pages dropped from index. Now, there is one very interesting thing there. First my home page was indexed on jan 02 and then again on jan 17th, i noticed Googlebot "deep crawled" just 6-7 pages 2-3 days ago. Those pages showed up in cache.

My question is, what can I expect? Should the bot do full deep crawl soon? If it does will the pages show as cached?

Also PR is behaving strange. It disappeared on 80% of pages in the last 3-4 days and then last night showed up again on all pages. This never happened before. Any similar experiences, or maybe explanations for all this?