During startup:

com.sun.org.apache.xerces.internal.impl.io.MalformedByteSequenceException:
Invalid byte 1 of 1-byte UTF-8 sequence.
	at
com.sun.org.apache.xerces.internal.impl.io.UTF8Reader.invalidByte(UTF8Reader.java:674)
[....]
	at
com.sun.org.apache.xerces.internal.jaxp.SAXParserImpl$JAXPSAXParser.parse(SAXParserImpl.java:522)
	at
org.netbeans.modules.welcome.content.CombinationRSSFeed.buildItemList(CombinationRSSFeed.java:62)
[catch] at org.netbeans.modules.welcome.content.RSSFeed$Reload.run(RSSFeed.java:158)

or

org.xml.sax.SAXParseException: Invalid byte 1 of 1-byte UTF-8 sequence.
	at
com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1269)
	at
org.netbeans.modules.welcome.content.CombinationRSSFeed.buildItemList(CombinationRSSFeed.java:62)
[catch] at org.netbeans.modules.welcome.content.RSSFeed$Reload.run(RSSFeed.java:158)
CONFIG [null]: Parse error in file http://www.netbeans.org/mtmo.xml line 22
column 434 (PUBLIC null)

The bogus line is

    <description>The tutorial will guide you through the creation of a sample
application which uses JNI to execute some native code written in the C
programming language. You will start off by creating a simple Java project,
adding a native method to it and then implementing this method in C using
NetBeans C/C++ Pack 5.5. This is the first part of the tutorial that covers the
creation of a sample JNI application in the Microsoft® Windows® operating
system.</description>

which apparently is attempting to use the (R) symbol in a UTF-8 document but
encodes it as (I guess) ISO-8859-1.

Please, fix your publishing script to run an XML validation tool *before*
pushing a new version of any XML file. Then fix it to correct the encoding of
incoming pages which are summarized.