Commenting feature broken

I've just noticed this morning that the anti-spam questions on this blog's comment form are playing up, refusing to accept what are in fact correct answers and hence making it effectively impossible to comment on anything. I have no idea what is causing this or how long this has been the situation - I'm working on fixing it as quickly as I can spare time for it at the moment, hopefully I'll have something figured out soon. Naturally, if the fix happens to be interesting I'll post details here. Apologies to anybody who has had comments lost on account of this. If you desperately want to comment on something in the mean time, email your comment to me and I'll happily add it manually for you.