Thanks steven.
Your .htaccess works. No more 500 or 404 errors now. But I noticed that your thread url is in the format of
http://domain.com/forums/t100.html
My thread url is in the format of
http://domain.com/forums/t100/s.html
and it leads to a 404 page as i am using fastforward's hack instructions for step 2 and 3.
May i know what did you use to replace (step 2 & 3)
<a href="$bburl/f$forum[forumid]/s$session[sessionhash]">$forum[title]</a>
<a href="$bburl/t$thread[threadid]/s$session[sessionhash].html">$thread[title]</a>
Thanks a lot.
Byron