Well, that was nice, wasn't it? We have the forum up for a day, and then it goes down again
Fortunately I was able to get through to tech support a lot faster this time and get it running again.
I'm still not sure exactly why the forum goes down - what specifically is causing the outages. However, the best guess I've come up with after talking to computer-savvy people is that the forum can't handle people posting messages every five seconds and the like. To (hopefully) help keep the forum running, I've set the flood interval (time you must wait between posts) to 15. I know this is inconvenient, but if it helps keep the forum up, I hope you'll agree that it's worth it.
EDIT: just a note, I've changed the number of threads per page from 30 to 20, in hope of A) preventing crashes, and B) generally speeding up loading time.
Sorry for the trouble!