It looks like it was the web host that caused the crash..
They had moved the site over to a new server without telling me.
It can take 24-28 hours before the domain name points to the new server, and it doesn't happen simultaneous all over the world, so some members may have posted on the old server, and some on the new one during this period..
That, or the copy process itself may have caused the missing database tables..
If I had known about this I could have disabled the forum for the duration of the move, and nothing would have happened..
THANKS FOR NOT TELLING ME THAT!!!....
It took me 12+ hours to fix this, and I still need to fix a couple of things before it's 100% again....