It is a common occurance when you are reading or writing and they clear the board to one page. Happens all the time. Just have to re-logon.
Last night it happened several times. When I logged on again they were down to one thread and it was about the Nagant Rifle because it was the last one posted, it was around 4 in the morning eastern time.
I decided it was time to go back to bed.
HQ