pandorasbox
As a new poster, you have daily posting limit. Simon has it posted here somewhere. After a month (I think), your limit will go up.
One reason for this, is to prevent spammers from joining. If they have a low limit of posts, they cannot effectively spam the board before being detected.
Once you've reached your 24-hour posting limit, let's say it's 5. Post #6 will remain processing, until 24 hours after your first post. It should remain 'in processing', then voila, it appears, perhaps several pages later. So, the posts 'stack up'. Sometimes they get lost.
My account was having this happen after we switched over to the new forum... yeah, frustrating. But Simon is tweaking, and it's good to let him know when having problems.
Simon has written about this, so that's loosely how it works, my details are sketchy. xx tal