From FB post
One important thing that people forget to do is consider what might happen with a circuit that has anything that draws power from the protoboard.
If you’re working with a few low power devices such as small LEDs and switches, then there is usually not a problem.
But if you have a buzzer driven by a transistor, the current may be high enough to cause the supply voltage on the protoboard to drop, and that may cause the device to sense that a switch was falsely pressed. The results may be very odd behavior.
The solution is to put a few bypass capacitors across the power supply lines on the protoboard. Something between 0.1 uF up to 10 uF will usually prevent or cure the problem.