check the event below. remove the URL property fixes the problem.
BEGIN:VEVENT^M
CREATED:20060209T091355Z^M
LAST-MODIFIED:20060209T091544Z^M
DTSTAMP:20060209T091355Z^M
UID:uuid1139476544012^M
SUMMARY:Vonk Vindt site nieuw^M
PRIORITY:1^M
CLASS:PUBLIC^M
DTSTART:20060220T110000^M
DTEND:20060220T120000^M
URL:http://www.vrijborg.nl/index.php?page=route ^M
X-LIC-ERROR:No value for STATUS property. Removing entire property:^M
LOCATION:Vrijborg\, Vughterweg 47-b\, 5211 CK\, Den Bosch^M
X-OPS-PROJECTID:A7AD2828-E869-41F1-B9E5-ABEB74BEC4AE^M
END:VEVENT^M
Logged In: YES
user_id=1333676
Originator: YES
upgrade to latest ical4j