Tabel crasher

Hej

Table './tblfakturaer' is marked as crashed and last (automatic?) repair failed

Jeg har følgende tabel som er crashed 2 gange på 1 uge.

CREATE TABLE IF NOT EXISTS `tblfakturaer` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `lagerstyring` tinyint(4) DEFAULT '0',
  `layout` text COLLATE utf8_danish_ci,
  `pdflayout` int(11) NOT NULL,
  `sendmail` tinyint(4) NOT NULL DEFAULT '0',
  `dato` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `stel` varchar(50) COLLATE utf8_danish_ci NOT NULL DEFAULT '',
  `ean` varchar(13) COLLATE utf8_danish_ci DEFAULT NULL,
  `firma` varchar(255) COLLATE utf8_danish_ci DEFAULT NULL,
  `navn1` varchar(255) COLLATE utf8_danish_ci NOT NULL DEFAULT '',
  `navn2` varchar(255) COLLATE utf8_danish_ci DEFAULT NULL,
  `adresse1` varchar(255) COLLATE utf8_danish_ci DEFAULT NULL,
  `adresse2` varchar(255) COLLATE utf8_danish_ci DEFAULT NULL,
  `postnr` varchar(10) COLLATE utf8_danish_ci DEFAULT NULL,
  `city` varchar(255) COLLATE utf8_danish_ci DEFAULT NULL,
  `land` varchar(255) COLLATE utf8_danish_ci DEFAULT NULL,
  `telefon` int(10) DEFAULT NULL,
  `email` varchar(200) COLLATE utf8_danish_ci NOT NULL DEFAULT '',
  `intref` varchar(100) COLLATE utf8_danish_ci DEFAULT NULL,
  `eksref` varchar(100) COLLATE utf8_danish_ci DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COLLATE=utf8_danish_ci AUTO_INCREMENT=4744 ;


Hvad kan skyldes at den crasher?