Blocking on lock for Dfs object?

Hi all, we are encountering lock issues with Dfs object that are nearly 
constant since Jan 5 with a system that has been working for two years. 
Stack trace of stuck thread in weblogic below, showing wait on lock on Dfs 
object. Any ideas on where we hunt for cause?

<Jan 27, 2015 10:13:51 PM EST> <Error> <WebLogicServer> <BEA-000337> 
<[STUCK] ExecuteThread: '14' for queue: 'weblogic.kernel.Default (self-
tuning)' has been busy for "634" seconds working on the request 
"weblogic.work.SelfTuningWorkManagerImpl$WorkAdapterImpl@11234004", which is 
more than the configured time (StuckThreadMaxTime) of "600" seconds. Stack 
trace:
Thread-171 "[STUCK] ExecuteThread: '14' for queue: 'weblogic.kernel.Default 
(self-tuning)'" <alive, suspended, blocked, priority=1, DAEMON> {
    -- Blocked trying to get lock: jcifs.smb.Dfs@115a1358[fat lock]
    jcifs.smb.Dfs.resolve(Dfs.java:159)
    jcifs.smb.SmbFile.resolveDfs(SmbFile.java:666)
    jcifs.smb.SmbFile.send(SmbFile.java:773)
    jcifs.smb.SmbFile.open0(SmbFile.java:972)
    jcifs.smb.SmbFile.open(SmbFile.java:1003)
    jcifs.smb.SmbFileOutputStream.<init>(SmbFileOutputStream.java:123)
    jcifs.smb.SmbFileOutputStream.<init>(SmbFileOutputStream.java:97)
    jcifs.smb.SmbFileOutputStream.<init>(SmbFileOutputStream.java:67)
    
com.cintas.filenet.invoice.signature.SignaturePDFMessageImpl.getFileShareCon
nection(SignaturePDFMessageImpl.java:145)
    
com.cintas.filenet.invoice.signature.SignaturePDFMessageImpl.convertImageToP
DF(SignaturePDFMessageImpl.java:78)
    
com.cintas.filenet.invoice.signature.SignaturePDFMessageImpl.onMessage(Signa
turePDFMessageImpl.java:49)
    weblogic.ejb.container.internal.MDListener.execute(MDListener.java:403)
    
weblogic.ejb.container.internal.MDListener.transactionalOnMessage(MDListener
.java:352)
    
weblogic.ejb.container.internal.MDListener.onMessage(MDListener.java:264)
    weblogic.jms.client.JMSSession.onMessage(JMSSession.java:4638)
    weblogic.jms.client.JMSSession.execute(JMSSession.java:4134)
    weblogic.jms.client.JMSSession.executeMessage(JMSSession.java:3820)
    weblogic.jms.client.JMSSession.access$000(JMSSession.java:115)
    weblogic.jms.client.JMSSession$UseForRunnable.run(JMSSession.java:5170)
    
weblogic.work.SelfTuningWorkManagerImpl$WorkAdapterImpl.run(SelfTuningWorkMa
nagerImpl.java:528)
    weblogic.work.ExecuteThread.execute(ExecuteThread.java:198)
    weblogic.work.ExecuteThread.run(ExecuteThread.java:165)
}