I am using umbraco 4.7.0 with .net 4. I have a slideshow where my news are displayed on homepage. News source is a rss feed created by xslt. I can display and see slideshow without any problem but when you click one of the news in the slideshow, it should direct you news detail page but upon clicking I got following error.

A potentially dangerous Request.QueryString value was 
detected from the client (~/<link xmlns:media="...helper">  <a 
href="/news/k...").

I searched for that issue on the net and tried in web.config like in the following

<httpRuntime requestValidationMode="2.0" />

<pages validateRequest="false" />

but those suggestion did not work out so after searching in umbraco, I found that I should add below code in the master template

<umbraco:DisableRequestValidation runat="server"/> 

but this time when you click one of news in slideshow, it redirects you "page not found" error page set in umbracoSettings.config.

I also add code snippet which causes that error in xslt file

<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet
  version="1.0"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:rssdatehelper="urn:rssdatehelper"
  xmlns:dc="http://purl.org/dc/elements/1.1/"
  xmlns:content="http://purl.org/rss/1.0/modules/content/"
  xmlns:msxml="urn:schemas-microsoft-com:xslt" 
  xmlns:umbraco.library="urn:umbraco.library" xmlns:Exslt.ExsltCommon="urn:Exslt.ExsltCommon" xmlns:Exslt.ExsltDatesAndTimes="urn:Exslt.ExsltDatesAndTimes" xmlns:Exslt.ExsltMath="urn:Exslt.ExsltMath" xmlns:Exslt.ExsltRegularExpressions="urn:Exslt.ExsltRegularExpressions" xmlns:Exslt.ExsltStrings="urn:Exslt.ExsltStrings" xmlns:Exslt.ExsltSets="urn:Exslt.ExsltSets" xmlns:tagsLib="urn:tagsLib" xmlns:BlogLibrary="urn:BlogLibrary" 
  xmlns:media="http://search.yahoo.com/mrss/" exclude-result-prefixes="msxml
 umbraco.library Exslt.ExsltCommon Exslt.ExsltDatesAndTimes 
Exslt.ExsltMath Exslt.ExsltRegularExpressions Exslt.ExsltStrings 
Exslt.ExsltSets tagsLib BlogLibrary ">


  <xsl:output method="xml" omit-xml-declaration="yes"/>
  <xsl:include href="../xslt/LanguageParameter.xslt" />
  <xsl:include href="../xslt/PropertyReferenceTranslation.xslt" />
  <xsl:param name="currentPage"/>

  <!-- Update these variables to modify the feed -->
  <xsl:variable name="RSSNoItems" select="string('200')"/>
  <xsl:variable name="RSSTitle" select="string('My sample rss')"/>
  <xsl:variable name="SiteURL" select="concat('http://', string(umbraco.library:RequestServerVariables('HTTP_HOST')))"/>
  <xsl:variable name="RSSDescription" select="string('Add your description here')"/>

  <!-- This gets all news and events and orders by updateDate to use for the pubDate in RSS feed -->
  <xsl:variable name="pubDate">
    <xsl:for-each select="$currentPage/* [@isDoc]">
      <xsl:sort select="@createDate" data-type="text" order="descending" />
      <xsl:if test="position() = 1">
        <xsl:value-of select="updateDate" />
      </xsl:if>
    </xsl:for-each>
  </xsl:variable>

  <xsl:template match="/">
    <!-- change the mimetype for the current page to xml -->
    <xsl:value-of select="umbraco.library:ChangeContentType('text/xml')"/>

    <xsl:text disable-output-escaping="yes">&lt;?xml version="1.0" encoding="UTF-8"?&gt;</xsl:text>
    <rss version="2.0"
    xmlns:media="http://search.yahoo.com/mrss/"
    xmlns:content="http://purl.org/rss/1.0/modules/content/"
    xmlns:wfw="http://wellformedweb.org/CommentAPI/"
    xmlns:dc="http://purl.org/dc/elements/1.1/">

      <channel>
        <title>
          <xsl:value-of select="$RSSTitle"/>
        </title>
        <link>
          <xsl:value-of select="$SiteURL" />
        </link>
        <pubDate>
          <xsl:value-of select="$pubDate"/>
        </pubDate>
        <generator>umbraco</generator>
        <description>
          <xsl:value-of select="$RSSDescription"/>
        </description>
        <language>en</language>

        <xsl:apply-templates select="$currentPage/* [@isDoc and string(umbracoNaviHide) != '1']">
          <xsl:sort select="@createDate" order="descending" />
        </xsl:apply-templates>
      </channel>
    </rss>

  </xsl:template>

  <xsl:template match="* [@isDoc]">
    <xsl:if test="position() &lt;= $RSSNoItems">
      <item>
        <title>
          <!--<xsl:value-of select="@nodeName"/>   --> 
                  <xsl:call-template name="PropertyReferenceTranslation">
                    <xsl:with-param name="nodeId" select="@id" />
                    <xsl:with-param name="Property" select="'title'" /> 
                    <xsl:with-param name="langISO" select="$langISO" />
                  </xsl:call-template>      
        </title>
        <link>
          <!--<xsl:value-of select="$SiteURL"/><xsl:value-of select="umbraco.library:NiceUrl(@id)"/>-->
          <a href="{concat(umbraco.library:NiceUrl(@id), '?lang=', $langISO)}" ></a>
        </link>
        <description>
          <!--<xsl:value-of select="newsDescription" disable-output-escaping="yes"/>-->  
                 <xsl:call-template name="PropertyReferenceTranslation">
                    <xsl:with-param name="nodeId" select="@id" />
                    <xsl:with-param name="Property" select="'newsDescription'" /> 
                    <xsl:with-param name="langISO" select="$langISO" />
                  </xsl:call-template>
        </description>      
        <pubDate>
          <xsl:value-of select="umbraco.library:FormatDateTime(@createDate,'r')" />
        </pubDate>
        <dc:date.Taken>
          <xsl:value-of select="umbraco.library:FormatDateTime(@createDate,'r')" />
        </dc:date.Taken>
        <author>
           <xsl:value-of select="@writerName"/>
         </author>        
         <guid>
           <xsl:value-of select="$SiteURL"/>
           <xsl:value-of select="umbraco.library:NiceUrl(@id)"/>
         </guid>
        <media:content url="{umbracoFile}" />
        <media:title type="plain">
                  <xsl:call-template name="PropertyReferenceTranslation">
                    <xsl:with-param name="nodeId" select="@id" />
                    <xsl:with-param name="Property" select="'title'" /> 
                    <xsl:with-param name="langISO" select="$langISO" />
                  </xsl:call-template>          
          <!--<xsl:value-of select="title"/>-->  
        </media:title>
        <media:description type="html">
                  <xsl:call-template name="PropertyReferenceTranslation">
                    <xsl:with-param name="nodeId" select="@id" />
                    <xsl:with-param name="Property" select="'newsDescription'" /> 
                    <xsl:with-param name="langISO" select="$langISO" />
                  </xsl:call-template>
          <!--<xsl:value-of select="newsDescription"/>-->  
        </media:description>
        <media:credit role="Software Developer">*</media:credit>     
      </item>
    </xsl:if>
  </xsl:template>

</xsl:stylesheet>