USB_Init() no longer calls sei() to enable global interrupts - this must now be done in the user application once all init code has run.

Projects/Magstripe/Magstripe.c

@@ -76,6 +76,8 @@ int main(void)
 	
 	for (uint8_t Buffer = 0; Buffer < TOTAL_TRACKS; Buffer++)
 	  BitBuffer_Init(&TrackDataBuffers[Buffer]);
+	  
+	sei();
 
 	for (;;)
 	{

Projects/Magstripe/Magstripe.h

@@ -41,6 +41,7 @@
 		#include <avr/io.h>
 		#include <avr/wdt.h>
 		#include <avr/power.h>
+		#include <avr/interrupt.h>
 
 		#include "Descriptors.h"
 		#include "Lib/MagstripeHW.h"