It has just been brought to my attention that PMs weren't working here for regular users. I don't know when this happened, but I can only guess it was during one of the various updates of the board software that I carry out from time to time, and something went slightly wrong behind the scenes.
It should be fixed now. I hope that nothing else was affected, but I was unaware there was anything wrong. So I'm sorry for any inconvenience or frustration that this has caused anyone.