I'm getting:

[DEBUG] updates\hudson.tasks.Maven.MavenInstaller file
[DEBUG] updates\hudson.tools.JDKInstaller file
[DEBUG] userContent\rack.gif file
[DEBUG] userContent\readme.txt file
[DEBUG] users\louis_davis\config.xml file
[DEBUG] users\william_leara\config.xml file
[DEBUG] Workspace clean-up.log file
[ERROR] org.codehaus.plexus.archiver.ArchiverException: Problem creating zip: The process cannot access the file because another process has locked a portion of the file
org.jvnet.hudson.plugins.backup.BackupException: java.io.IOException: org.codehaus.plexus.archiver.ArchiverException: Problem creating zip: The process cannot access the file because another process has locked a portion of the file
at org.jvnet.hudson.plugins.backup.utils.BackupEngine.doBackup(BackupEngine.java:115)
at org.jvnet.hudson.plugins.backup.utils.BackupTask.run(BackupTask.java:125)
at java.lang.Thread.run(Unknown Source)
Caused by: java.io.IOException: org.codehaus.plexus.archiver.ArchiverException: Problem creating zip: The process cannot access the file because another process has locked a portion of the file
at org.jvnet.hudson.plugins.backup.utils.BackupEngine.handleEnd(BackupEngine.java:104)
at org.apache.commons.io.DirectoryWalker.walk(DirectoryWalker.java:336)
at org.jvnet.hudson.plugins.backup.utils.BackupEngine.doBackup(BackupEngine.java:113)
... 2 more
[ INFO] Cancel hudson shutdown mode
[ INFO] Backup end at [03/10/10 12:37:59]
[ INFO] [49.641s]

• option set to create zip file
• verbose mode is on
• all 4 checkboxes under "Backup content" are unchecked

This exact same setup used to work, but one day stopped. Can anyone give me some advice on troubleshooting what might be holding which file in use? Perhaps a plugin I installed is causing the trouble?