I have to agree with DJ Freshfluke , sounds like a power issue . Add up the Wattage for your equipemnt before plugging into that outlet , always use two seprerate outlets , on different circuits . Never Never hookup a Fog machine to the same outlet as your main . If it s a 15 amp circuit take 15x120volts = 1800 watts 20 Amp circuit 20x120volts = 2400 Watts
Now if you bring a Dry Ice Machine with you , it has to be also on a seperate outlet . Dry Ice machines use 13 amp out of the 15 amp . What you can also do is hookup your VMS4 at home just hookup your main equipment , nothing else , and see if this still happens. You may want to invest in a Power conditioner , that will show the voltage in a digital readout . You do not want to go under 110 volts .