I had the same problem, brother - I made an update on my Intro thread. It was there all afternoon, all evening, and then POOF! it was gone. I also noticed that the "views" of that thread had dropped aswell.
Also, I made a few Greetings! posts to our new members - and late last night they also disappeared. There was even one post, and I remember this clearly, from a Canadian Muslim in Toronto - her first post - I was the first to respond in welcoming her and POOF! the entire thread is gone.
I don't know what is going on. I felt as it Shaiitan was trying to undermine our progress here or something in the form of a technical glitch, if you know what I mean.
I do not have many technical skills to offer much advice, but I just wanted to confirm Brother Kayote's post. I hope this isn't happening rampantly. May I suggest double-checking your internal security and data integrity?
Assalamu Alaikum =)