Hacked
I'm not sure when it happened as I've been out and about recently, but at some point this blog was "hacked" and some suspect code ended up causing a few problems. I've updated WordPress and resolved the issue. Posting frequency will still be down until I'm back to work and whatnot, but fear not, I shall return.
The fact that it was hacked shows that your blog is interesting enough for someone to take some time trying to get into it.