I am a new mac user and a sound similar to the "Frog" sound effect keeps playing at random times and with no apparent reason. It just plays and at different times...Sometimes it's every 20 seconds, sometimes more or less. I disabled the sound in System Preferences and it kept playing. I don't know what else to do since i'm new with mac... I also reseted the PRAM and it stopped for a while but now it started again. I've noticed that most of the times it sounds when i'm charging the battery, i don't know if it has something to do. Help me please! Thanks.