I posted a message a short time ago about cracking rafters (it's still there) and when I went into my office today I noticed that the ceiling tiles are buckling. I have to repair this immediately before they come down on my head, but I was wondering if the cracking rafter sound had anything to do with this? I checked up in the attic again and didn't notice anything different. I also did an internet search on repairing/replacing ceiling tiles and it kept mentioning ceiling joist. My other question is could the ceiling joist have shifted? Now I'm getting scared!