htaccess Elite

I can access my main website page but any other page returns a 404 Not Found Error. When I contacted tech support for my Host they keep pointing to a problem with my .htaccess file. I am currently using BANS software and have uploaded the original file as well as a complete backup from 10/11/09 when it was still working. I'm still receiving this error. They say that the redirects are not working. Anyone have any ideas what to look at? Thanks in advance.