Ho controllato tutti i titoli delle notizie contenuti nella categoria in questione (anche se il problema si è manifestato solo in una categoria e da circa tre giorni), e non contengono caratteri speciali.
Di seguito l'HTML del popup:
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<title>Titolo : 1.1.2</title>
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<ul>
<li id="general_tab" class="current"><span><a href="javascript:mcTabs.displayTab('general_tab','general_panel');" onMouseDown="return false;">Generale</a></span></li>
<li id="events_tab"><span><a href="javascript:mcTabs.displayTab('events_tab','events_panel');" onMouseDown="return false;">Eventi</a></span></li>
<li id="advanced_tab"><span><a href="javascript:mcTabs.displayTab('advanced_tab','advanced_panel');" onMouseDown="return false;">Avanzate</a></span></li>
</ul>
</div>
<div class="panel_wrapper" style="border-bottom:0px;">
<div id="general_panel" class="panel current">
<fieldset>
<legend>Generale</legend>
<table border="0" cellpadding="4" cellspacing="0">
<tr>
<td nowrap="nowrap"><label id="hreflabel" for="href">URL</label></td>
<td>
<table border="0" cellspacing="0" cellpadding="0">
<tr>
<td colspan="2"><input id="href" name="href" type="text" value="" size="150" /></td>
</tr>
</table>
</td>
</tr>
<tr>
<td class="column1"><label for="anchorlist">Ancora</label></td>
<td colspan="2" id="anchorlistcontainer"> </td>
</tr>
<tr>
<td><label id="targetlistlabel" for="targetlist">Target</label></td>
<td><select id="targetlist" name="targetlist">
<option value="_self">Apri in questa finestra / frame</option>
<option value="_blank">Apri in nuova finestra</option>
<option value="_parent">Aprine nella finestra / frame parent</option>
<option value="_top">Apri nel top frame (rimpiazza tutti i frame)</option>
</select>
</td>
</tr>
<tr>
<td nowrap="nowrap"><label id="titlelabel" for="title">Titolo</label></td>
<td><input id="title" name="title" type="text" value="" /></td>
</tr>
<tr>
<td><label id="classlabel" for="classlist">Classe</label></td>
<td>
<select id="classlist" name="classlist" onChange="changeClass();">
<option value="" selected>-Non impostato-</option>
<option value="jcebox">jcebox</option>
</select>
</td>
</tr>
</table>
</fieldset>
<fieldset>
<legend><strong>indirizzo E-Mail</strong></legend>
<table border="0" cellpadding="4" cellspacing="0">
<tr id="emailaddressrow">
<td class="column1"><label for="emailadd">Indirizzo</label></td>
<td><input id="emailadd" name="emailadd" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="emailsub">Soggetto</label></td>
<td><input id="emailsub" name="emailsub" type="text" value="" /></td>
</tr>
<tr>
<td colspan="2"><input id="emailcreate" class="button" type="button" onClick="buildAddress();" value="Crea" /></td>
</tr>
</table>
</fieldset>
</div>
<div id="advanced_panel" class="panel">
<fieldset>
<legend>Avanzate</legend>
<table border="0" cellpadding="0" cellspacing="4">
<tr>
<td class="column1"><label id="idlabel" for="id">Id</label></td>
<td><input id="id" name="id" type="text" value="" /></td>
</tr>
<tr>
<td><label id="stylelabel" for="style">Stile</label></td>
<td><input type="text" id="style" name="style" value="" /></td>
</tr>
<tr>
<td><label id="classeslabel" for="classes">Classe</label></td>
<td><input type="text" id="classes" name="classes" value="" onChange="selectByValue('classlist',this.value,true);" /></td>
</tr>
<tr>
<td><label id="targetlabel" for="target">Nome Target</label></td>
<td><input type="text" id="target" name="target" value="" onChange="selectByValue('targetlist',this.value,true);" /></td>
</tr>
<tr>
<td class="column1"><label id="dirlabel" for="dir">Direzione Lingua</label></td>
<td>
<select id="dir" name="dir">
<option value="">-Non impostato-</option>
<option value="ltr">Da sinistra a destra</option>
<option value="rtl">Da destra a sinistra</option>
</select>
</td>
</tr>
<tr>
<td><label id="hreflanglabel" for="hreflang">Lingua Target</label></td>
<td><input type="text" id="hreflang" name="hreflang" value="" /></td>
</tr>
<tr>
<td class="column1"><label id="langlabel" for="lang">Codice Lingua</label></td>
<td>
<input id="lang" name="lang" type="text" value="" />
</td>
</tr>
<tr>
<td><label id="charsetlabel" for="charset">Codifica Carattere Target</label></td>
<td><input type="text" id="charset" name="charset" value="" /></td>
</tr>
<tr>
<td><label id="typelabel" for="type">Target MIME type</label></td>
<td><input type="text" id="type" name="type" value="" /></td>
</tr>
<tr>
<td><label id="rellabel" for="rel">Relazione pagina - target</label></td>
<td><select id="rel" name="rel" class="mceEditableSelect">
<option value="">-Non impostato-</option>
<option value="alternate">Alternate</option>
<option value="designates">Designates</option>
<option value="stylesheet">Stylesheet</option>
<option value="start">Start</option>
<option value="next">Next</option>
<option value="prev">Prev</option>
<option value="contents">Contents</option>
<option value="index">Index</option>
<option value="glossary">Glossary</option>
<option value="copyright">Copyright</option>
<option value="chapter">Chapter</option>
<option value="subsection">Subsection</option>
<option value="appendix">Appendix</option>
<option value="help">Help</option>
<option value="bookmark">Bookmark</option>
</select>
</td>
</tr>
<tr>
<td><label id="revlabel" for="rev">Relazione target - pagina</label></td>
<td><select id="rev" name="rev">
<option value="">-Non impostato-</option>
<option value="alternate">Alternate</option>
<option value="designates">Designates</option>
<option value="stylesheet">Stylesheet</option>
<option value="start">Start</option>
<option value="next">Next</option>
<option value="prev">Prev</option>
<option value="contents">Contents</option>
<option value="index">Index</option>
<option value="glossary">Glossary</option>
<option value="copyright">Copyright</option>
<option value="chapter">Chapter</option>
<option value="subsection">Subsection</option>
<option value="appendix">Appendix</option>
<option value="help">Help</option>
<option value="bookmark">Bookmark</option>
</select>
</td>
</tr>
<tr>
<td><label id="tabindexlabel" for="tabindex">Tabindex</label></td>
<td><input type="text" id="tabindex" name="tabindex" value="" /></td>
</tr>
<tr>
<td><label id="accesskeylabel" for="accesskey">Accesskey</label></td>
<td><input type="text" id="accesskey" name="accesskey" value="" /></td>
</tr>
</table>
</fieldset>
</div>
<div id="events_panel" class="panel">
<fieldset>
<legend>Eventi</legend>
<table border="0" cellpadding="0" cellspacing="4">
<tr>
<td class="column1"><label for="onfocus">onfocus</label></td>
<td><input id="onfocus" name="onfocus" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="onblur">onblur</label></td>
<td><input id="onblur" name="onblur" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="onclick">onclick</label></td>
<td><input id="onclick" name="onclick" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="ondblclick">ondblclick</label></td>
<td><input id="ondblclick" name="ondblclick" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="onmousedown">onmousedown</label></td>
<td><input id="onmousedown" name="onmousedown" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="onmouseup">onmouseup</label></td>
<td><input id="onmouseup" name="onmouseup" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="onmouseover">onmouseover</label></td>
<td><input id="onmouseover" name="onmouseover" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="onmousemove">onmousemove</label></td>
<td><input id="onmousemove" name="onmousemove" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="onmouseout">onmouseout</label></td>
<td><input id="onmouseout" name="onmouseout" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="onkeypress">onkeypress</label></td>
<td><input id="onkeypress" name="onkeypress" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="onkeydown">onkeydown</label></td>
<td><input id="onkeydown" name="onkeydown" type="text" value="" /></td>
</tr>
<tr>
<td class="column1"><label for="onkeyup">onkeyup</label></td>
<td><input id="onkeyup" name="onkeyup" type="text" value="" /></td>
</tr>
</table>
</fieldset>
</div>
</div>
<div class="panel_wrapper" style="border-top:0px;">
<fieldset>
<legend><strong>Joomla! Collegamenti ai contenuti</strong></legend>
<table border="0" style="height:100px; text-align:center;">
<tr>
<td><img id="loader" src="../mambots/editors/jce/jscripts/tiny_mce/libraries/images/spacer.gif" width="16" height="16" /></td>
<td class="label" valign="middle" nowrap>Seleziona Tipologia</td>
<td><select class="link_select" name="list_type" onChange="if(this.value!=''){clearLists();loadType(this.value,'');}">
<option value="">--Seleziona Tipologia--</option><option value="section_link">Sezione</option><option value="section_select_category">Categoria</option><option value="section_select_article">Articolo</option><option value="static_link">Contenuto Statico</option><option value="category_select_weblink">Collegamento Web</option><option value="category_select_contact">Contatti</option><option value="menu_link">Menu</option> </select>
</td>
</tr>
<tr>
<td> </td>
<td id="list_level_1_label" class="label" valign="middle" nowrap> </td>
<td colspan="2"><div id="list_level_1"> </div></td>
</tr>
<tr>
<td> </td>
<td id="list_level_2_label" class="label" valign="middle" nowrap> </td>
<td><div id="list_level_2"> </div></td>
</tr>
<tr>
<td> </td>
<td id="list_level_3_label" class="label" valign="middle" nowrap> </td>
<td><div id="list_level_3"> </div></td>
</tr>
</table>
</fieldset>
</div>
<div class="mceActionPanel">
<div style="float: left">
<input type="button" id="insert" name="insert" value="{$lang_insert}" onClick="insertAction();" />
</div>
<div style="float: right">
<input type="button" class="button" id="help" name="help" value="Aiuto" onClick="openHelp();" />
<input type="button" id="cancel" name="cancel" value="Annulla" onClick="tinyMCEPopup.close();" />
</div>
</div>
</form>
</body>
</html>