I am glad that you have found a fault. It is very rare indeed for a wound solenoid to lower its DC resistance. It could still be a wiring error if you somehow have two solenoids connected in parallel. Almost certainly the extra load is dropping the voltage to the point where it falls below the level where the voltage regulator feeding the Pi cannot provide a stable 5 volts DC and, it falls over.

Remember that DC resistance (R) is different from AC impedance (Z). http://hyperphysics.phy-astr.gsu.edu/hbase/electric/imped.html. That’s why I initially suggested that you measure the actual current drawn with an AC Ammeter. Nonetheless a 50% difference between one solenoid and the others would make me very suspicious indeed. I would completely remove the suspect solenoid and check it out of circuit. If it still exhibits the same problem then, it’s off to Home depot or Lowes.