ho cancellato e poi installato nuovamente Arduino 
ma niente
come si inserisce in tag code ?
sketch_apr08a:5: error: 'IRrecv' does not name a type
sketch_apr08a:7: error: 'decode_results' does not name a type
sketch_apr08a.ino: In function 'void setup()':
sketch_apr08a:12: error: 'irrecv' was not declared in this scope
sketch_apr08a.ino: In function 'void loop()':
sketch_apr08a:16: error: 'irrecv' was not declared in this scope
sketch_apr08a:16: error: 'results' was not declared in this scope