Notification Locks - Lucene

We have recently been getting the following locks. I'll restart and see if they go away, but I'm guessing something's locked that shouldn't have:

Build CPA Jobbie: Could not notify listeners that the build has completed (Occurrences 1)
(java.io.IOException: Lock obtain timed out: Lock@C:\DOCUME~1\KHANMO~1\LOCALS~1\Temp\lucene-5e9748f5b787eb7de57bd123c94c89eb-write.lock)
Strack Trace

java.io.IOException: Lock obtain timed out: Lock@C:\DOCUME~1\KHANMO~1\LOCALS~1\Temp\lucene-5e9748f5b787eb7de57bd123c94c89eb-write.lock
at org.apache.lucene.store.Lock.obtain(Lock.java:58)
at org.apache.lucene.index.IndexWriter.(IndexWriter.java:255)
at org.apache.lucene.index.IndexWriter.(IndexWriter.java:225)
at com.atlassian.bamboo.index.IndexConnectionManager.getWriter(IndexConnectionManager.java:77)
at com.atlassian.bamboo.index.IndexConnectionManager.index(IndexConnectionManager.java:67)
at com.atlassian.bamboo.index.DefaultTestCaseResultsIndexer.indexTestCaseResult(DefaultTestCaseResultsIndexer.java:137)
at com.atlassian.bamboo.index.DefaultTestCaseResultsIndexer.indexTestCaseResults(DefaultTestCaseResultsIndexer.java:129)
at com.atlassian.bamboo.index.DefaultTestCaseResultsIndexer.indexBuildResultKeepConnection(DefaultTestCaseResultsIndexer.java:112)
at com.atlassian.bamboo.index.DefaultTestCaseResultsIndexer.indexBuildResult(DefaultTestCaseResultsIndexer.java:59)
at com.atlassian.bamboo.event.BuildCompleteNotifier.doTask(BuildCompleteNotifier.java:70)
at com.atlassian.bamboo.container.BambooTask.run(BambooTask.java:33)
at java.lang.Thread.run(Unknown Source)