Indexed pages are declining

I have the same problem, after installing vBA i went from 51.200 to around 30.000 last week and today 23.800.
Also when i typed www.mydomain.nl in google search all my forums were listed, now i only see member profiles and some topics......

vBA changes the linking structure of your site. In most cases, all of your sub-forum links get moved off that page. Since your homepage typically has the best link value, once all those sub-forum links are moved off, they are another step away, and share less of the link value.

Do some housecleaning with vBA. Get any unnecessary links off the page (for guests at least), and make sure the content on the page is actually related to your theme and not maintenance notices, etc.

Make sure the remaining links you have on the homepage are to valuable resources, and not something like currently online users, etc, which will not provide you any SEO value, and will diminish SEO value for other pages.

A month later (May 2008)

google: 38.400 (from 29.600)

yahoo: Pages (58,748) | Inlinks (21) (from 49,500)

msn: 439 (from 876)

we removed vba.

So - you've seen improvement in your indexed page count again. How about your traffic?