Further to a post on the EPE site and a conversation with James:
I am now going to use three LM317 to set separate voltages 5V, 2.5V and 1.25V to supply 100mA. I want to switch these three separate voltages ON/OFF with three micro I/O pins. Can I switch the LM317 ON/OFF with an NPN in series between the bottom R2 resistor and GND. Would this switching ON/OFF in this manner crash the LM317 on startup?