something making my oscam files 0 bytes

last night about this time my server went off

when i ftp i see the oscam config user and server all gone to 0?

i have to upload a back to get the server working again

any help? how do i check cron jobs?

or has someone uploaded a file, still here and cant get it back online

well after swopping usb hub, was ok for a hr and went again, on each reboot said unknown in readers in oscam and even tried via pc the same, 2 hrs of luck to get working, but what caused it?