I cleared the cache & cookies 10 days ago after trying the program that promises to speed up your mac (which I refuse to ever mention by name) but had the opposite effect and really screwed up my mac.
I'm on Firefox 12, and broadband via the telephone line and then wifi link.
I think its connected to losing the publicize link to Facebook and Twitter, which I reinstated once, but nothing happened, so I reinstated it again. This was since my last post 3 or 4 days ago when I noticed it hadn't appeared on facebook. I was asked to allow wordpress to manage my pages (?) and I 'allowed'. Though I don't really understand what that means.
I corrected the problem when I realised it was a 'new' post that had appeared, so I trashed it, and back to normal. One of those weird things I suppose!