Hi Cillian,
sorry, the weekend got away from me a little.
My suggestions are going to seem really really obvious, sorry in advance, but good to check these things out.
1) Did logging in/out work before?
2) What changed since then?
Can you change back to the default themes in bbPress and WordPress and then do the following, noting your server error log along the way (after each step):
3) navigate away form your website, then clear your cookies, the restart your browser.
4) Try and login via your bbPress.
5) navigate away form your website, then clear your cookies, the restart your browser.
6) Try and login via WordPress
7) navigate away form your website, then clear your cookies, the restart your browser.
try and register with bbPress
9) navigate away form your website, then clear your cookies, the restart your browser.
10) Register via WordPress.
I know those steps are painful, and a bit pedantic, but cookies are a VERY big pain if they don’t work first time when integrating these two systems (especially if you’re logged in as admin/keymaster at the time of installation/integration). Right now, it appears you’re in the 1% rather than the 99% mate, but lets try and fix that.
Kev