By the sounds of your description you have setup the nas with two separate disks both of which appear to be giving problems all of a sudden.
Have you changed anything on your network, updated router, changed wireless setup, added more devices etc.?
You say something 'appears to reboot', is this in fact the nas actually rebooting i.e. being off the network for a couple of minutes while the reboot takes place, or is it something else like the video restarting?
Have you run the S.M.A.R.T test (management ->disk management -> s.m.a.r.t test) and if so what were the results?
Looking at those things should give some indication of where the problem lies.