And..... You are going to have more problems shortly. 4 AA batteries = something less than 6 volts into the regulator, which means that the regulator is just barely working - unless you've got a LDO (low drop out) regulator. Either add another AA cell so the input to the regulator is ~7.5 volts, or replace the regulator with a diode - 1N4148, etc. - to drop the 6 volts from the 4 AA cells to about 5.3 volts.