If you get it again make it known and I'll fix it. There's a forum setting to disallow forms on other sites (or any cross-origin HTTP requests, I assume) to send posts and private messages to this forum (i.e. post/message without being on the forum). For security reasons this is a good thing, but there are a number of reports of forumotion's own forms breaking this for whatever reason. It doesn't seem to happen often, and if the problem disappears on its own I don't really feel the need to disable it, but if it happens enough to be an actual nuisance I'll get rid of it.
NNID: drakeirving2A Colorful Calculating Creative and Cuddly Crafty Callipygous Clever Commander