BuddyPress.org

First let start out by saying I have read every st on the net about the pemalinks breaking to get 404 errors. I have not found relating to this issue specifically.

Problem

All links on the site work EXCEPT post links. Any post in the forum does not work and produces a 404 error. The correct url according to the permalink setting is showing in the address bar.

Attempts to solve:
htacess, server modules etc have all been scrutinized by 3 sys admins and have been shown to be working just fine. In fact this server is running other wp installs including a buddypress install. We know the server is not the issue as logic would have us believe.

Permalink setting
We have tried all permalinks settings and found no positive result to resolve.

Install, reinstall, upgrade
Yes, we installed both wp and bp many times. We tried various versions in various combinations without success. Same issue.

Any idea of where to look.