put a PSCN to a WIFI, put another WIFI then spark it, if there are many particles or your cpu is not strong enough, the WIFI attaching to the PSCN will continuous spark, while it should give one spark instead
More seriously, once this happened, even there's only one pixel of WIFI, it will give current itself without input. To fix this, you have to hit the NEW button or delete amount of particles to rise the FPS