Por que recebo uma MalformedInputException desse código?

Sou novato em Scala e queria escrever alguns códigos-fonte para melhorar. Eu escrevi um objeto simples (com uma entrada principal) para simular uma chamada "grep" em todos os arquivos do diretório atual. (Eu inicio o programa do Eclipse Indigo, e no Debian Squeeze):

package com.gmail.bernabe.laurent.scala.tests

import java.io.File

import scala.io.Source

object DealWithFiles {

  def main(args:Array[String]){
    for (result <- grepFilesHere(".*aur.*"))
      println(result)
  }

  private def grepFilesHere(pattern:String):Array[String] = {
    val filesHere = new File(".").listFiles

    def linesOfFile(file:File) =
      Source.fromFile(file).getLines.toList

    for (file <- filesHere;
        if file.isFile
    )
      yield linesOfFile(file)(0)
  }

}

Mas eu recebo um java.nio.charset.MalformedInputException, que não consigo resolver:

Exception in thread "main" java.nio.charset.MalformedInputException: Input length = 1
at java.nio.charset.CoderResult.throwException(CoderResult.java:260)
at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:319)
at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:158)
at java.io.InputStreamReader.read(InputStreamReader.java:167)
at java.io.BufferedReader.fill(BufferedReader.java:136)
at java.io.BufferedReader.readLine(BufferedReader.java:299)
at java.io.BufferedReader.readLine(BufferedReader.java:362)
at scala.io.BufferedSource$BufferedLineIterator.hasNext(BufferedSource.scala:67)
at scala.collection.Iterator$class.foreach(Iterator.scala:772)
at scala.io.BufferedSource$BufferedLineIterator.foreach(BufferedSource.scala:43)
at scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:48)
at scala.collection.mutable.ListBuffer.$plus$plus$eq(ListBuffer.scala:130)
at scala.collection.TraversableOnce$class.toList(TraversableOnce.scala:242)
at scala.io.BufferedSource$BufferedLineIterator.toList(BufferedSource.scala:43)
at com.gmail.bernabe.laurent.scala.tests.DealWithFiles$.linesOfFile$1(DealWithFiles.scala:18)
at com.gmail.bernabe.laurent.scala.tests.DealWithFiles$anonfun$grepFilesHere$2.apply(DealWithFiles.scala:23)
at com.gmail.bernabe.laurent.scala.tests.DealWithFiles$anonfun$grepFilesHere$2.apply(DealWithFiles.scala:20)
at scala.collection.TraversableLike$WithFilter$anonfun$map$2.apply(TraversableLike.scala:697)
at scala.collection.IndexedSeqOptimized$class.foreach(IndexedSeqOptimized.scala:34)
at scala.collection.mutable.ArrayOps.foreach(ArrayOps.scala:38)
at scala.collection.TraversableLike$WithFilter.map(TraversableLike.scala:696)   
at com.gmail.bernabe.laurent.scala.tests.DealWithFiles$.grepFilesHere(DealWithFiles.scala:20)
at com.gmail.bernabe.laurent.scala.tests.DealWithFiles$.main(DealWithFiles.scala:10)
at com.gmail.bernabe.laurent.scala.tests.DealWithFiles.main(DealWithFiles.scala)

Agradecemos antecipadamente por ajuda :)

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