IE skips the 'toString' method in a for( var attr in objext ) loop. (http://webreflection.blogspot.com/2007/07/quick-fix-internet-explorer-and.html) therefore when an object is extended by $.extend, a toString method is not copied.

fix on line 605 in version 1.3.2 add

if( options.toString != {}.toString ) {

// copy any overruled toString method

target.toString = options.toString;

}