So, apparently some people are having problems.
Some can't post?
For some, the "My Messages" just doesn't show, at all, or gives an "access error" trying to access PM's (In one case, while logged in, only "Home" "Help" "Profile" and "Logout" show up).
For some, Accessing the "Summary" part of their Profile results in "access error" or redirects to Account Settings.
I've been unable to replicate or find a cause, even suspending CF Cache (and subsequently flushing it) resulted in no changes to affected users.
Reporting was done via IRC and Discord.