strange java error for simple loop files process

I have a simple process where a loop files operator reads a directory of SPSS data files and then converts/writes them as csv files. The process appears to work fine for some directories, but for other directories it generates an unexplained "process failed" error. It seems to be some kind of java error, but I am not sure why this process is working in some cases and not in others. All the directories are in the same general location but are just different subdirectories. The information from the log file is shown below. Any help would be appreciated.

Apr 06, 2016 9:55:40 AM com.rapidminer.Process loadInitialData
INFO: Loading initial data.
Apr 06, 2016 9:55:40 AM com.rapidminer.Process run
INFO: Process //BrianRepository/Learning/Misc/convert SPSS files starts
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread run
SEVERE: Process failed: operator cannot be executed. Check the log messages...
java.lang.IndexOutOfBoundsException
at java.io.FileInputStream.readBytes(Native Method)
at java.io.FileInputStream.read(FileInputStream.java:255)
at com.rapidminer.operator.io.BytewiseExampleSource.read(BytewiseExampleSource.java:127)
at com.rapidminer.operator.io.BytewiseExampleSource.read(BytewiseExampleSource.java:119)
at com.rapidminer.extension.file.connectors.operator.io.SPSSExampleSource.readStream(SPSSExampleSource.java:335)
at com.rapidminer.operator.io.BytewiseExampleSource.createExampleSet(BytewiseExampleSource.java:84)
at com.rapidminer.operator.io.AbstractExampleSource.read(AbstractExampleSource.java:49)
at com.rapidminer.operator.io.AbstractExampleSource.read(AbstractExampleSource.java:33)
at com.rapidminer.operator.io.AbstractReader.doWork(AbstractReader.java:126)
at com.rapidminer.operator.Operator.execute(Operator.java:1000)
at com.rapidminer.operator.execution.SimpleUnitExecutor.execute(SimpleUnitExecutor.java:50)
at com.rapidminer.operator.ExecutionUnit.execute(ExecutionUnit.java:798)
at com.rapidminer.operator.OperatorChain.doWork(OperatorChain.java:392)
at com.rapidminer.operator.meta.AbstractFileIterator.doWorkForSingleIterationStep(AbstractFileIterator.java:128)
at com.rapidminer.operator.meta.FileIterator.iterate(FileIterator.java:103)
at com.rapidminer.operator.meta.AbstractFileIterator.doWork(AbstractFileIterator.java:109)
at com.rapidminer.operator.meta.FileIterator.doWork(FileIterator.java:59)
at com.rapidminer.operator.Operator.execute(Operator.java:1000)
at com.rapidminer.operator.execution.SimpleUnitExecutor.execute(SimpleUnitExecutor.java:50)
at com.rapidminer.operator.ExecutionUnit.execute(ExecutionUnit.java:798)
at com.rapidminer.operator.OperatorChain.doWork(OperatorChain.java:392)
at com.rapidminer.operator.Operator.execute(Operator.java:1000)
at com.rapidminer.Process.run(Process.java:1071)
at com.rapidminer.Process.run(Process.java:973)
at com.rapidminer.Process.run(Process.java:926)
at com.rapidminer.Process.run(Process.java:921)
at com.rapidminer.Process.run(Process.java:911)
at com.rapidminer.gui.ProcessThread.run(ProcessThread.java:65)

Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: Here:
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: Process[1] (Process)
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: subprocess 'Main Process'
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: +- Loop Files[1] (Loop Files)
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: subprocess 'Nested Process'
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: ==> | +- Read SPSS[1] (Read SPSS)
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: | +- Write CSV[0] (Write CSV)
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: +- Loop Zip-File Entries[0] (Loop Zip-File Entries)
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: subprocess 'Nested Process'
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: +- Read SPSS (2)[0] (Read SPSS)
Apr 06, 2016 9:55:41 AM com.rapidminer.gui.ProcessThread logProcessTreeList
SEVERE: +- Write CSV (2)[0] (Write CSV)