Yes, My indexed page count has dropped as well, however the visitor count not. I think google flushes the pages that are indexed, but contains inofrmation that havent been search for long time. Maybe I'm vrong?
mine too. But mine are small. From 4000 to I am rite know on 126. Still not able to find the reason why.
I have not experienced a "large" drop, just around 5,000 - 6,000 pages, no big deal. My forum still has around 109,000 indexed. What I can tell you, I have seen 20,000 - 30,000 pages disappear overnight, then take a week or two to get indexed again. Total pages indexed by google can go up or down, so dont worry about it. The more pages you have, the more you may loss. If I lose 5,000 or 10,000 pages its not big deal. But if a website owner whos site only has 11,000 pages, that might be a really big deal. One thing to take into consideration, is your site map getting updated to google correctly? Have you checked your google webmaster tools for sitemap errors? If you are really concerned, then start at with your google webmaster tools and go from there. Also check your server logs - has the server been restarted or downed for service? Even if it was at 2am or 3am, if the hosting company shut the server down to replace a hard drive or memory. While the server was down google could have tried to access your site, this could affect your URLs as well. One night I shutdown the site to restore a database. I guess the total downtime was about 2 hours. The next day I lost almost 100,000 URLs for my site. It took about a week but google reindexed them again and everything was fine.