I have made the following changes in the last month.
Url re-write to html
title from topic and forum
dynamic Mete-tag / keywords
I was listed on the first page on google for about 15 key words that were awesome for my forums subject. Since these changes I am not even in the top 10,0000 for any of them any more..
Worried and confused?? I am tempted to go back to my non-dynamic title and meta desc..