Wow, this plugin just saved my day - thank you.
But I have a problem. Before, I used vBSeo. Thread-URLs were like forum.com/forum-title/../threadtitle-threadID WITHOUT .html
I dont care much having html or not, but the old links do not work now. Links from google are all horribly wrong and get redirected to my front page. Any solution for this please? fast maybe?

Allready tried this:
RewriteRule [^/]+/[^/]+-([0-9]+) http://www.domain.com/showthread.php?t=$1 [L,R=301]
It redirects correctly, but damages another plugin and some pictures on my site.
beside that, german umlauts like ?, ? and ? do not work in urls? I allready set utf8..