Oops, sorry. I didn’t realize you were already using that one. I don’t believe there is a compatibility issue with 3.5. I’m using it on a number of 3.5 sites with no problems. There could be an issue with another plugin, but the error message you’re getting makes me think it may just be an issue with the Google XML Sitemaps plugin itself.
The first thing I would do is check to make sure the file http://www.eaptherapy.com/wp-content/plugins/google-sitemap-generator/sitemap.xsl is there on your server, that its size is 4 KB, and that its permissions are 644. You can also download it and make sure its contents look like this:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="2.0"
xmlns:html="http://www.w3.org/TR/REC-html40"
xmlns:sitemap="http://www.sitemaps.org/schemas/sitemap/0.9"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="html" version="1.0" encoding="UTF-8" indent="yes"/>
<xsl:template match="/">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>XML Sitemap</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<style type="text/css">
body {
font-family:"Lucida Grande","Lucida Sans Unicode",Tahoma,Verdana;
font-size:13px;
}
#intro {
background-color:#CFEBF7;
border:1px #2580B2 solid;
padding:5px 13px 5px 13px;
margin:10px;
}
#intro p {
line-height: 16.8667px;
}
td {
font-size:11px;
}
th {
text-align:left;
padding-right:30px;
font-size:11px;
}
tr.high {
background-color:whitesmoke;
}
#footer {
padding:2px;
margin:10px;
font-size:8pt;
color:gray;
}
#footer a {
color:gray;
}
a {
color:black;
}
</style>
</head>
<body>
<h1>XML Sitemap</h1>
<div id="intro">
<p>
This is a XML Sitemap which is supposed to be processed by search engines like <a href="http://www.google.com">Google</a>, <a href="http://search.msn.com">MSN Search</a> and <a href="http://www.yahoo.com">YAHOO</a>.<br />
It was generated using the Blogging-Software <a href="http://wordpress.org/">WordPress</a> and the <a href="http://www.arnebrachhold.de/redir/sitemap-home/" title="Google Sitemap Generator Plugin for WordPress">Google Sitemap Generator Plugin</a> by <a href="http://www.arnebrachhold.de/">Arne Brachhold</a>.<br />
You can find more information about XML sitemaps on <a href="http://sitemaps.org">sitemaps.org</a> and Google's <a href="http://code.google.com/sm_thirdparty.html">list of sitemap programs</a>.
</p>
</div>
<div id="content">
<table cellpadding="5">
<tr style="border-bottom:1px black solid;">
<th>URL</th>
<th>Priority</th>
<th>Change Frequency</th>
<th>LastChange (GMT)</th>
</tr>
<xsl:variable name="lower" select="'abcdefghijklmnopqrstuvwxyz'"/>
<xsl:variable name="upper" select="'ABCDEFGHIJKLMNOPQRSTUVWXYZ'"/>
<xsl:for-each select="sitemap:urlset/sitemap:url">
<tr>
<xsl:if test="position() mod 2 != 1">
<xsl:attribute name="class">high</xsl:attribute>
</xsl:if>
<td>
<xsl:variable name="itemURL">
<xsl:value-of select="sitemap:loc"/>
</xsl:variable>
<a href="{$itemURL}">
<xsl:value-of select="sitemap:loc"/>
</a>
</td>
<td>
<xsl:value-of select="concat(sitemap:priority*100,'%')"/>
</td>
<td>
<xsl:value-of select="concat(translate(substring(sitemap:changefreq, 1, 1),concat($lower, $upper),concat($upper, $lower)),substring(sitemap:changefreq, 2))"/>
</td>
<td>
<xsl:value-of select="concat(substring(sitemap:lastmod,0,11),concat(' ', substring(sitemap:lastmod,12,5)))"/>
</td>
</tr>
</xsl:for-each>
</table>
</div>
<div id="footer">
Generated with <a href="http://www.arnebrachhold.de/redir/sitemap-home/" title="Google Sitemap Generator Plugin for WordPress">Google Sitemap Generator Plugin for WordPress</a> by <a href="http://www.arnebrachhold.de/">Arne Brachhold</a>. This XSLT template is released under GPL.
</div>
</body>
</html>
</xsl:template>
</xsl:stylesheet>
If all that looks good, I think I would next try uninstalling and reinstalling the Google XML Sitemaps plugin and retest.
If none of that fixes it, then go Settings -> XML-Sitemap and click the “rebuild your sitemap” link, then retest.
If it’s still broken, click the “debug function” link to get more info and post what you find here.
