There are couple of different reasons why a pinball game will fire multiple solenoids when the machine is turned on, and/or a game is started. Depending on when and how the solenoids are firing will determine which steps you take next.
The first scenario is when you turn on the game (this can often be intermittent) several solenoids all fire at once. This indicates a problem with the blanking circuit, which should prevent solenoids from firing until the CPU has completely booted up. If you are having this problem see XXX.
The next possibility is that several solenoids will fire sequentially (rather than all at once as described above) when the game is powered on. This may also happen when you begin a new game or sometimes even during a game.
In this case the machine cannot find all of the pinballs, or in some cases is confused because it finds too many pinballs. In either case the game goes into search mode and will fire solenoids one at a time until it finds all of the balls or gives up after 10-30 seconds. For this problem see XXX.