Well I'm an idiot - the fulltext index on page_text was missing from a default installation. It didn't break searches but probably slowed them down tremendously. Also set engine to MyISAM on page_text to avoid cryptic error messages from MySQL.

.mceItemFlash {
	border: 1px dotted #cc0000;
	background-image: url('../images/flash.gif');
	background-position: center;
	background-repeat: no-repeat;
	background-color: #ffffcc;
}