svn: MERGE of '/svn/<RepositoryName>/shelvesets': 409 Conflict (<ServerName>)

OS: Windows Server 2003 R2. Client Server: Windows XP Professional 2002, SP 2
SVN version 1.6.3, File System repository structure
Built custom pre- and post-commit hooks, which make various svn calls to examine transaction, allow the commit, then examing the revision to extract information for future use.
The version of Berkeley DB you're running Subversion with, if any
Using variouse IDEs with client plug-ins such as TortoiseSVN, JDeveloper 11g, Eclipse, etc. All of these IDEs support SVN 1.6.

We have several repositories that have been running under VisualSVN Server Manager 2.0.4 since October 2009. Multiple users have been accessing this repository without any major issues.
Yesterday, I, as Subversion Administrator, attempted to create a new folder using Tortoise SVN 1.6.6. I was not able to do so, receiving a 403 error. After several other administrators
received the same error, we restarted the SVN server, then the server box itself. Now we are receiving the following message when we try to create a new folder:

 org.tigris.subversion.svnclientadapter.SVNClientException: org.tigris.subversion.javahl.ClientException: svn: Commit blocked by pre-commit hook (exit code 123) with output:
The filename, directory name, or volume label syntax is incorrect.
svn: MERGE of '/svn/<RepositoryName>/shelvesets': 409 Conflict (<ServerName>)
        at org.tigris.subversion.svnclientadapter.javahl.AbstractJhlClientAdapter.mkdir(AbstractJhlClientAdapter.java:2310)
        at org.tigris.subversion.svnclientadapter.javahl.AbstractJhlClientAdapter.mkdir(AbstractJhlClientAdapter.java:896)
        at oracle.jdevimpl.vcs.svn.op.SVNOperationNewRemoteDir$NewRemoteDirTask.executeMkdirWithProgress(SVNOperationNewRemoteDir.java:342)
        at oracle.jdevimpl.vcs.svn.op.SVNOperationNewRemoteDir$NewRemoteDirTask.run(SVNOperationNewRemoteDir.java:223)
        at java.lang.Thread.run(Thread.java:619)
Caused by: org.tigris.subversion.javahl.ClientException: svn: Commit blocked by pre-commit hook (exit code 123) with output:
The filename, directory name, or volume label syntax is incorrect.
svn: MERGE of '/svn//<RepositoryName>//shelvesets': 409 Conflict (<ServerName>)
        at org.tigris.subversion.javahl.JavaHLObjectFactory.throwException(JavaHLObjectFactory.java:777)
        at org.tmatesoft.svn.core.javahl.SVNClientImpl.throwException(SVNClientImpl.java:1850)
        at org.tmatesoft.svn.core.javahl.SVNClientImpl.mkdir(SVNClientImpl.java:836)
        at org.tigris.subversion.svnclientadapter.javahl.AbstractJhlClientAdapter.mkdir(AbstractJhlClientAdapter.java:2307)
        ... 4 more
Caused by: org.tmatesoft.svn.core.SVNException: svn: Commit blocked by pre-commit hook (exit code 123) with output:
The filename, directory name, or volume label syntax is incorrect.
svn: MERGE of '/svn//<RepositoryName>//shelvesets': 409 Conflict (<ServerName>)
        at org.tmatesoft.svn.core.internal.wc.SVNErrorManager.error(SVNErrorManager.java:64)
        at org.tmatesoft.svn.core.internal.wc.SVNErrorManager.error(SVNErrorManager.java:51)
        at org.tmatesoft.svn.core.internal.io.dav.DAVCommitEditor.closeEdit(DAVCommitEditor.java:373)
        at org.tmatesoft.svn.core.wc.SVNCommitClient.doMkDir(SVNCommitClient.java:480)
        at org.tmatesoft.svn.core.javahl.SVNClientImpl.mkdir(SVNClientImpl.java:834)
        ... 5 more

When we commented out the calls within the pre- and post-commit cmd files, we were able to create the folders without a problem.

To our knowledge, nothing has changed on the server, including the pre- and post-commit hooks, which have been operating for months without a problem.

Please note, the names of the server and repository have been redacted for security reasons,.

Larry Kriv
Configuration Management
Healthcare Product Technology
HP Enterprise Services
Telephone +1 972.605.2654
Email larry.kriv_at_hp.com
5400 Legacy Drive, H1-5D-82 / Plano, TX 75024