Spark suddenly quit loading

I am new to Spark, but was pretty impressed with the softare.  As a result, I installed it and it has been working fine. 

I have one particular computer that suddenly quit loading Spark.  I double-click on the ICON and nothing seems to happen.  I decided to run Task Manager to see if Spark.exe even loads when I double-click.  It does load, but then it exits quickly thereafter.

I did a search on the forums and found some odd-ball post that ClearType interferes with Spark sometimes, so I disabled it, but I still can't get Spark to load.  Keep in mind, this machine was running Spark without any issues for the last 2 months.  I deleted the error log and ran it again so I could get a fresh copy of what was happening.  Here's the error log text:

java.lang.reflect.InvocationTargetException

          at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

          at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

          at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

          at java.lang.reflect.Method.invoke(Unknown Source)

          at org.jivesoftware.launcher.Startup.start(Startup.java:94)

          at org.jivesoftware.launcher.Startup.main(Startup.java:44)

          at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

          at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

          at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

          at java.lang.reflect.Method.invoke(Unknown Source)

          at com.exe4j.runtime.LauncherEngine.launch(Unknown Source)

          at com.exe4j.runtime.WinLauncher.main(Unknown Source)

Caused by: java.lang.ExceptionInInitializerError

          at org.jivesoftware.spark.PluginManager.deleteOldPlugins(PluginManager.java:189)

          at org.jivesoftware.spark.PluginManager.movePlugins(PluginManager.java:131)

          at org.jivesoftware.spark.PluginManager.<init>(PluginManager.java:115)

          at org.jivesoftware.spark.PluginManager.getInstance(PluginManager.java:97)

          at org.jivesoftware.Spark.startup(Spark.java:208)

          ... 12 more

Caused by: java.nio.channels.OverlappingFileLockException

          at sun.nio.ch.FileChannelImpl$SharedFileLockTable.checkList(Unknown Source)

          at sun.nio.ch.FileChannelImpl$SharedFileLockTable.add(Unknown Source)

          at sun.nio.ch.FileChannelImpl.tryLock(Unknown Source)

          at java.nio.channels.FileChannel.tryLock(Unknown Source)

          at java.util.logging.FileHandler.openFiles(Unknown Source)

          at java.util.logging.FileHandler.<init>(Unknown Source)

          at org.jivesoftware.spark.util.log.Log.<clinit>(Log.java:59)

          ... 17 more