EasyBuzzer went into conflict with IRremote libraries. I solved by changing the timer selection from 2 to 1 in IRremote's boarddefs.h file:
// Arduino Mega
#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
#define IR_USE_TIMER1 // tx = pin 11
//#define IR_USE_TIMER2 // tx = pin 9
...
EasyBuzzer went into conflict with IRremote libraries. I solved by changing the timer selection from 2 to 1 in IRremote's boarddefs.h file: