Google dropping my pages

slowly but steadily

[NazaretH]

Google used to have over 3000 pages indexed from my site - all unique pages, with unique content, titles, and external links.

Now Google is dropping pages by portions of 50-100 every couple of days. Now it is already only 2000 pages in the index. Meanwhile the site is growing and already has over 10000 pages for Google to index.

Can anyone suggest what could be the reason of this? The site has PR4... do you think that higher PR might help?

Rankings of the indexed pages seem to be not affected; traffic is decreasing proportionally to the amount of dropped pages.