I've seen this issue many times. A laser printer plugged into the same AC leg as a UPS protected computer. When the laser printer kicks in, it causes a brownout on that leg. The UPS never reacts fast enough and the computer shuts down. Well I think it does not react AT ALL, given it's not really an outage, just a brownout. My old printer used to do this and I was lucky enough that the hallway plug was on the other leg so I used to plug it in that plug. Now my parent's is doing the same thing. It seems to be random as sometimes you can get away with it and it wont happen. What is the solution to this issue? I'm thinking some kind of capacitor bank, but that would require a rectifier and inverter. Would be rather expensive I would think. What about an isolation transformer, would that do any good? I can't see how though. I can't be the only one who has seen this issue before. What is a common solution?