Official comment
The problem is not the forum, but the change in browser security regarding cookies / data. If you change the security settings on this site to allow 3rd party cookies and cross-domain data, it will work properly.
You should do that as well as clear the existing cookies and cache for:
*.pioneerdj.com
*.rekordbox.com
*.kuvo.com
*.zendesk.com
*.gigya.com
Doing so will result in the ability to login here and any of our sites without issue.