diff -r dee028db6e9b -r 73bdfa70b04e src/net/fortuna/ical4j/model/component/VFreeBusy.java
--- a/src/net/fortuna/ical4j/model/component/VFreeBusy.java	Tue Feb 10 19:25:00 2015 +0100
+++ b/src/net/fortuna/ical4j/model/component/VFreeBusy.java	Tue Feb 10 19:38:00 2015 +0100
@@ -398,7 +398,7 @@
                 final Period period = (Period) i.next();
                 // check if period outside bounds..
                 if (!range.intersects(period)) {
-                    periods.remove(period);
+                    i.remove();
                 }
             }
             return new FreeBusy(periods);
@@ -628,7 +628,6 @@
             PropertyValidator.getInstance().assertOne(Property.ORGANIZER, getProperties());
             PropertyValidator.getInstance().assertOne(Property.UID, getProperties());
             
-            PropertyValidator.getInstance().assertOneOrLess(Property.COMMENT, getProperties());
             PropertyValidator.getInstance().assertOneOrLess(Property.URL, getProperties());
             
             PropertyValidator.getInstance().assertNone(Property.ATTENDEE, getProperties());
@@ -687,7 +686,6 @@
             PropertyValidator.getInstance().assertOne(Property.ORGANIZER, getProperties());
             PropertyValidator.getInstance().assertOne(Property.UID, getProperties());
             
-            PropertyValidator.getInstance().assertOneOrLess(Property.COMMENT, getProperties());
             PropertyValidator.getInstance().assertOneOrLess(Property.URL, getProperties());
             
             PropertyValidator.getInstance().assertNone(Property.DURATION, getProperties());
@@ -741,8 +739,6 @@
             PropertyValidator.getInstance().assertOne(Property.ORGANIZER, getProperties());
             PropertyValidator.getInstance().assertOne(Property.UID, getProperties());
             
-            PropertyValidator.getInstance().assertOneOrLess(Property.COMMENT, getProperties());
-            
             PropertyValidator.getInstance().assertNone(Property.FREEBUSY, getProperties());
             PropertyValidator.getInstance().assertNone(Property.DURATION, getProperties());
             PropertyValidator.getInstance().assertNone(Property.REQUEST_STATUS, getProperties());