NUnit parser can't parse categories

When trying to parse a certain test results file, the Bamboo log shows this error and the build fails. Sample test output attached:

2007-09-27 18:07:38,462 ERROR [BAM:Unit Test:BuildExe] [NUnitXmlTestResultsParser] Failed to parse xml test results. File name: test_results.xml. At path: C:\localdev\DotNet\Source\CheckCashing\CheckCashing.NUnit\bin\Debug\test_results.xml
org.xml.sax.SAXException: Don't know how to parse categories
at com.atlassian.bamboo.configuration.DefaultContentHandler.startElement(DefaultContentHandler.java:56)
at org.apache.xerces.parsers.AbstractSAXParser.startElement(Unknown Source)
at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanStartElement(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at com.atlassian.bamboo.plugin.builder.nant.NUnitXmlTestResultsParser.parse(NUnitXmlTestResultsParser.java:189)
at com.atlassian.bamboo.plugin.builder.nant.NUnitTestReportCollector.collect(NUnitTestReportCollector.java:44)
at com.atlassian.bamboo.plugin.builder.nant.AbstractDotNetBuilder$NUnitResultFileVisitor.visitFile(AbstractDotNetBuilder.java:86)
at com.atlassian.bamboo.utils.FileVisitor.visitAlLFilesThatMatchAPattern(FileVisitor.java:78)
at com.atlassian.bamboo.utils.FileVisitor.visitFilesThatMatch(FileVisitor.java:52)
at com.atlassian.bamboo.plugin.builder.nant.AbstractDotNetBuilder.collateTestResults(AbstractDotNetBuilder.java:117)
at com.atlassian.bamboo.builder.AbstractBuilder.build(AbstractBuilder.java:214)
at com.atlassian.bamboo.build.pipeline.tasks.ExecuteBuildTask.call(ExecuteBuildTask.java:48)
at edu.emory.mathcs.backport.java.util.concurrent.FutureTask.run(FutureTask.java:176)
at edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:987)
at edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:528)
at com.atlassian.bamboo.build.pipeline.concurrent.NamedThreadFactory$1.run(NamedThreadFactory.java:31)
at edu.emory.mathcs.backport.java.util.concurrent.helpers.ThreadHelpers$1.run(ThreadHelpers.java:34)
at java.lang.Thread.run(Unknown Source)