Let me just input my theoretical opinion on how this could happen:
1. Host company decides to begin migrating server data to another box.
2. At, say, 12:00, a copy is made of all the data on the servers.
3. At 12:05, Tiger guy and Alkaline post. The posts are submitted to the old server box that is still running, which remain there for about an hour.
4. At 12:30, the copy operation from the backup to the new server is complete. The new server is brought online, with a half-hour old forum database.
5. Everyone after Tiger Guy and Alkaline posts. Because the new server started with slightly old data, it appears as though Tiger Guy and Alkaline's posts were never there. Mysterious, isn't it?
6. The next day, Tiger Guy and Alkaline wake up to see that their helpful posts have been "deleted".
7. In their anger management ritual, they each take the de-barked trunk of a 15-year-old oak tree and lodge it in their rectum. The sudden expansion of their anus causes them intense pain and internal bleeding, which moves them to become increasingly aggressive as to inquiring where their posts have gone.