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.

Demos/Host/ClassDriver/MouseHostWithParser/MouseHostWithParser.c

@@ -68,6 +68,7 @@ int main(void)
 	SetupHardware();
 
 	puts_P(PSTR(ESC_FG_CYAN "Mouse Host Demo running.\r\n" ESC_FG_WHITE));
+	sei();
 
 	LEDs_SetAllLEDs(LEDMASK_USB_NOTREADY);