We can see this problem fails many testsuite tests:
http://hudson.jboss.org/hudson/view/JBoss%20AS/job/JBoss-AS-5.0.x-TestSuite-sun15/

tests-report-text:
[mkdir] Created dir: /qa/services/hudson/hudson_workspace/workspace/JBoss-AS-5.0.x-TestSuite-sun15/trunk/testsuite/output/reports/text
[style] Transforming into /qa/services/hudson/hudson_workspace/workspace/JBoss-AS-5.0.x-TestSuite-sun15/trunk/testsuite/output/reports/text
[style] Processing /qa/services/hudson/hudson_workspace/workspace/JBoss-AS-5.0.x-TestSuite-sun15/trunk/testsuite/output/reports/TESTS-TestSuites.xml to /qa/services/hudson/hudson_workspace/workspace/JBoss-AS-5.0.x-TestSuite-sun15/trunk/testsuite/output/reports/text/TESTS-TestSuites.txt
[style] Loading stylesheet /qa/services/hudson/hudson_workspace/workspace/JBoss-AS-5.0.x-TestSuite-sun15/trunk/testsuite/output/stylesheets/summary1b.xsl

BUILD FAILED
/qa/services/hudson/hudson_workspace/workspace/JBoss-AS-5.0.x-TestSuite-sun15/trunk/testsuite/build.xml:929: The following error occurred while executing this line:
java.lang.OutOfMemoryError: Java heap space