Honestly, and I’m not trying to give Chris or anybody else at WE a hard time: my suggestion is to dump this forum software like a bad date. WordPress is an excellent CMS platform - it is great for blogging, for general web sites, and for giving the non-technical user some semblance of power and control.
However, despite attempts, it is not software that can “do everything.” No software can pull that off. Find a forum specific software that does only forums; it’s going to be more reliable (how many crashes with lost data have you had this year? If you say more than zero, that’s too many, IMO), have a better feature set, enable better portability of data, all those things that are soon going to overwhelm you…including security.
Wordpress is a leading threat vector for attacks; sooner or later, it will happen to you. You will discover that somebody took advantage of known vulnerabilities in WordPress to compromise and control your site. It is virtually guaranteed in today’s web space, and it’s a real PITA when it does happen. I was the CTO at a hosting company, and I regret that we ever got involved with WordPress - supporting the security was a nightmare.
I would make another suggestion that goes with this: you have a forum on the Internet, which is great - and for many users, that’s all they will ever need or want. However, there is another class of user who is arguably at least as important, and they will never use an Internet-based forum: these are the FaceBook people. It’s a completely different dynamic, and a powerful dynamic. Businesses ignore this dynamic at their own peril; most businesses have, as part of their customer support and communication plan, the establishment of an Internet forum and the establishment of a Facebook forum.
(If I was more jaded, I might request that you get the Facebook stuff rolling soon, so that you keep the FacePlace people away from me over here; but I’m kinder and gentler these days, so I would never say that. I would just emphasize that the FacePlace people really do need their own space.)
As far as software goes, I know that vBulletin XenForo are popular. I have no idea of relative merits, nor of what else might be available. Might be worth a look.
I know, this is huge. I really do believe that it would, in the longer run, be worth it in terms of stable uptime, data retention, and security.