Google seems to be cleaning its index

Many webmasters (not only forum owners) are reporting large decreases in the number of indexed pages of their sites.

This is not entirely unusual. I have experienced this several times on different sites. Google seems to periodically remove many many indexed pages from a site, and then, within a few weeks, re-spiders them and re-indexes the pages.

Point being, dont panic. This is a good time to do some link building to your site, especially deep linking.

Dont tell me that! :)

I converted to vB because of this very same issue with phpBB indexing in google.

Google tends to flush parts of their index from time to time. I personally think there are problems with the Big Daddy infrastructure changes recently made. Many webmasters are reporting huge drops in indexed pages.. Not just vB owners, but others as well.