I was up in Canada With Easy Street and when we toured up there, we often hit a bunch of little cities in Ontario that hadn't been discovered yet. In one particular city, the name of which I don't remember, the stage was set up where the bar was about 40 feet and and 90 degrees to our left. (That becomes important later.) We set up, did sound check, all done by about 3 in the afternoon Monday.
Monday night we go down to play. I powered up my rig, which was 3 keyboards and a rack in those days. One of those was an Ensoniq Mirage (it WAS 1988 after all). Also a Korg Poly 6 and a Roland Juno 60. The Mirage required that an OS be loaded from a floppy, then samples loaded. And it was one at a time, so you had piano OR strings, but not both. I loaded up the piano to start the night with On The Dark Side. We played the song through. On to the next song, at which time ALL of my keyboards reset, meaning that I had to pop the OS disc back in and reboot the Mirage. I did that. Halfway through the second song it happened again. So I repeated the process. In the first 4 songs, I rebooted those keyboards 9 times.
I was frantic, trying to figure out why I was having problems and nobody else was. At break I got out sound guy involved. We traced and tracked and did whatever we could until I realized that I had taken my power from an outlet that was on the same circuit as the ice maker. Whenever that ice maker kicked in, the compressor drew so much power that my line level voltage was dropping to under 90, and my keyboards saw that as a power cycle. Who would have thought that an outlet over 40 feet away from the ice machine was going to be on the same circuit? So we ran some power from a different circuit and it was fine.