We had a bit of an influx of spammers recently, and decided to upgrade the forum software to improve security, since we were a few versions behind. However, the script we needed to run to upgrade the databases through to the new versions broke, and the phpbb website has been down for over a week so we're unable to find fixes.
In addition, with the increased size of the forum and the server running out of drive space, the forum crashed a few times and those crashes caused database corruptions, which in turn was causing the forums to randomly die.
We've decided to start fresh. When the phpbb site comes back up we'll fix the old forum databases and grab all important posts to copy back over here. We're starting fresh, though, to get rid of all inactive members and to have a smaller, non-corrupt, working database.
Unfortunately this means that you'll have to register again, but the forums should be a happier, more stable place from now on.