Check the timing, does it occur at approximately the same time each day? Does it occur at the same time something else happens? Had a similar problem years ago in a large office building, the computer would crash everyday between 3 and 4 PM. Finally traced it down to a large pump that was wired in with the computers power circuit. Some equipment would be drained by this pump at close to the end of each work day. Possibly you have it plugged in with something that that creates interference and turns on at the same time your equipment cuts out.