i am having a very similar problem. i am trying to drive 2 5v relays and a pic off a single 5v regulator. the relay coils are controlled by the PIC via 2n2222 transistors. the PIC works fine until i try to activate a relay, then it also freezes. i hav a LED across the regulator and that stays on (shows that 5v is stil present) if i remove the PIC from the circuit and manually activate the relay (5v from the reg to the base of the transistor) it works perfectly, however as soon as i put the PIC back into the circuit, and try to activate the relay manually again (not connected at all to the PIC), it seems to short out the regulator. Please help, it really makes no sense to me.