Apparently CF was causing an overload on the server hosting it via the sending out of large numbers of spam emails. This happened previously to cause the site to be taken down in January of this year, also the site had been hacked and was showing lots of drug ads originating from third world countries.
This time the site wasn't hacked as far as the ads, but the email barrage happened again and the discussion forum was pinpointed as the culprit and was disabled. I had no advance warning this was going to happen; like everyone else I went to the forum and received the "not found" message.
The past two weeks have been spent finding a new host for CF and migrating this very large site to a new server. The first one turned out to be incompetent or worse (most employees seem to be based in India) and after paying them three different times for ever more expensive hosting packages, my webmaster advised me to sign on with a different hosting company, and the board finally went back online last night around 2 or 3 in the morning Eastern time.
When I find out more information about what needs to be done to prevent another occurrence of the board being taken down I'll let everyone know. It could be that the forum will need to be upgraded, and/or the rest of the site rebuilt or ditched but that's just speculation at this point.