I think my server resetted itself somewhere around 1am this morning. This resulted in the system's date also being reset back to Jan 1 1996. If you posted a (new) message between 1am and 9am CEST, the message would not show because the system would think it was a 4 year old message.
I have just corrected the date and all new postings should be fine again, but since my plane leaves in a couple of hours, I am unable to correct the date for the messages posted in the past hours.
My apologies for any inconvenience.