Re: Buddypress installed on Windows Server
You really should search before posting, rather than have us do it 
this is most likely a mod_rewrite / .htaccess issue o in this instance on a windows server a lack of mod_rewrite.
It is a question that crops up many times, try this link for some info and follow it’s links as well.
https://buddypress.org/community/groups/installing-buddypress/forum/topic/rewrite-issues-page-not-found/
The WP Codex also has advice on url rewriting in particular on windows servers.
