Libraries incompatible: IRemote.cpp vs. NewPing.cpp

ISR(TIMER2_COMPA_vect) {    // NewPing.cpp:214
#define TIMER2_COMPA_vect _VECTOR(7)   /* Timer/Counter2 Compare Match A */

Yes it definitely looks like the Timer 2 compare "A" side interrupt vector.

This may or may not be easy to fix. It looks like both libraries use timer 2 for some purpose. Maybe one can be changed to use a different timer, maybe not. You would need a spare one. Looks like both libraries use Timer 2 only. Timer 0 is normally used for millis() and micros(). That would appear to leave Timer 1 free.