I know for a fact I posted in a thread. I saw my post. And when I went back to see if anyone had commented on what I had posted, my post was gone from the thread. What's that about?

did you post the thread in another forum as well? Because I know that 3FC removes threads that has been posted twice, to prevent spamming I guess.

It wasn't a thread I posted, it was merely a post in an existing thread.
And it went *poof* Twice that has happened.

Posts can be deleted at moderator discretion. Sometimes an entire thread is removed per OP request or if it has crossed aline. Sometimes part of a thread is removed if there was a problem midway and any posts that referred to it would also be removed as 'clean up'. I don't know which posts you are talking about but I'm sure they were removed for a reason, then life goes on