Guilty Guardian wrote...
sometimes my posts become invisible
That has happened to me as well, tough I also found situations that at some point no more posts for given thread would be showed, until I logged on again, say, a day or two later.
Interestingly, that has happened most in Chat and Forum Games section.
I also encountered the random 404 "wave" thing (I try to access something and it gives me a 404 or site maintenance message, until I refresh. Those will often occour quite often for several minutes and then stop).