sure you're busy enough with the forum counts problem, but here's one to think about.
I administer on 2 forums, one of them is pretty large and recently people with a space in their usernames haven't been receiving PM's. The problem is not with them but when someone clicks on the 'PM User' icon. It takes out all the gaps, and of course when they attempt to send it, it says 'no-one of that name is registered on the forum'?
We've also had instances of people trolling and some of the admins have tried to check out their PM's, but again if it's a user with a gap in their name you simply cannot open it up (it's ok for those with a single name or with an underscore between words)?
The other forum which I administer on is much smaller and is fine.