Really sorry about this, chaps.
We moved to a new (much better) backup system last night. Effectively, to date, we've run a nightly backup, so should the worst happen, we only lost 24 hour's worth of posts at the most. Under the new system, the SQL database is replicated live onto a remote server so theoretically, we should never lose data ever again. Sadly there was a glitch with the implementation of the new backup routine which meant things went screwy for a while.
It was fixed about 11am yesterday and you should no longer see any weirdness. Unfortunately, during the barf, posts made between 11.30pm Sunday evening and 11am Monday morning are almost certainly lost for good, unless they've reappeared meantime when we did a database reconstruction.
Sincere apologies if anything important was lost in that time.