To my horror, I logged into the site this afternoon and found that everyone was listed as unregistered. Even I couldn't login.

After connecting to the site, I noticed that the memberslist.cgi file was smaller than usual. I downloaded and checked it. Only to discover that it had a single entry in it. Obviously the last person to register on the site today.

Luckily, I had a backup of the file from a few weeks ago. So I uploaded that to the site and rebuilt the member metadata. This rebuilt the .cgi file.

Does anyone have ANY idea why something like this would happen or was the board hacked by someone who then deleted that file?

Our board is over here.

sounds like a hack job - we had something similar happen at UBBDev, but that was using a version previous to 6.3 and a script kiddie was automatically registering hundreds of people per minute, it corrupted the memberslist.cgi file and started writing over the older member files. Infopop fixed it soon after and I re-wrote 20-30 member files by hand :/

Anyways, be sure you have some sort of flood protection turned on, even if it's just 10 seconds - that'll foil most kiddie hackers so that at least it doesn't happen to you

Yeah, I figured that it may have been a hack job, but I'm at a loss as to how it could have been done. If he could hack into the site, why not just delete the user data files?

Beats me... it could still be a bug, but one I haven't heard of yet