NullPointerException at DeploymentSorter with IBM's JDK

I've a project working well with JBoss 4.0.3SP1 + Sun JDK 1.5.0_06. I start JBoss in debug mode and if I make a change to the class the "hot-code-replace" works well. But with IBM's JDK I get the following exception after making any change to a class:

02:04:10,212 ERROR [AbstractDeploymentScanner$ScannerThread] Scanning failed; continuing
java.lang.NullPointerException
at java.lang.String.endsWith(String.java :494)
at org.jboss.deployment.DeploymentSorter.getExtensionIndex (DeploymentSorter.java:84)
at org.jboss.deployment.DeploymentSorter.compare(DeploymentSorter.java:72)
at java.util.Arrays.mergeSort(Arrays.java:1299)
at java.util.Arrays.mergeSort (Arrays.java:1310)
at java.util.Arrays.mergeSort(Arrays.java:1310)
at java.util.Arrays.mergeSort(Arrays.java:1310)
at java.util.Arrays.sort(Arrays.java:1238)
at java.util.Collections.sort (Collections.java:174)
at org.jboss.deployment.scanner.URLDeploymentScanner.scan(URLDeploymentScanner.java:496)
at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.doScan (AbstractDeploymentScanner.java:192)
at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.loop (AbstractDeploymentScanner.java:203)
at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.run (AbstractDeploymentScanner.java:182)

That stack trace start appearing in logs after making a change to a class, and continue appearing again and again and again.