Forum Moderators: Robert Charlton & goodroi
Since you appear to have a fairly large site, the first thing I'd be looking at is your architecture.
Hot Topics [webmasterworld.com...] and duplicate content is a good place to start . Also , what links have put into the site.
How old is the site and what have you done to it ?
Checking off some of the basics may be helpful.
[edited by: Whitey at 12:41 am (utc) on Aug. 8, 2008]