diff --git a/java/src/org/broadinstitute/sting/gatk/datasources/simpleDataSources/ReferenceDataSource.java b/java/src/org/broadinstitute/sting/gatk/datasources/simpleDataSources/ReferenceDataSource.java
index 825131962..cc15f6b01 100644
--- a/java/src/org/broadinstitute/sting/gatk/datasources/simpleDataSources/ReferenceDataSource.java
+++ b/java/src/org/broadinstitute/sting/gatk/datasources/simpleDataSources/ReferenceDataSource.java
@@ -51,6 +51,16 @@ public class ReferenceDataSource implements ReferenceDataSourceProgressListener
      * @param fastaFile Fasta file to be used as reference
      */
     public ReferenceDataSource(File fastaFile) {
+
+        // does the fasta file exist? check that first...
+        if (!fastaFile.exists()) {
+            if (!fastaFile.getParentFile().exists())
+                throw new UserException("The fasta file path you provided is invalid. The directory " +
+                       fastaFile.getParentFile().getAbsolutePath() + " does not exist." );
+            else
+                throw new UserException("The fasta file you provided does not exist.");
+        }
+
         File indexFile = new File(fastaFile.getAbsolutePath() + ".fai");
         File dictFile;
         if (fastaFile.getAbsolutePath().endsWith("fa")) {
diff --git a/java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleDataSourceTest.java b/java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleDataSourceUnitTest.java
similarity index 98%
rename from java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleDataSourceTest.java
rename to java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleDataSourceUnitTest.java
index e66e6fce3..54b4f0658 100644
--- a/java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleDataSourceTest.java
+++ b/java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleDataSourceUnitTest.java
@@ -17,13 +17,13 @@ import java.util.Set;
  * Date: Sep 9, 2010
  * Time: 8:21:00 AM
  */
-public class SampleDataSourceTest extends BaseTest {
+public class SampleDataSourceUnitTest extends BaseTest {
 
     // this empty header used to instantiate sampledatasource objects
     private static SAMFileHeader header = new SAMFileHeader();
 
     // all the test sample files are located here
-    private String sampleFilesDir = validationDataLocation +  "sample/";
+    private String sampleFilesDir = validationDataLocation +  "samples/";
 
     // make sure samples are created from the SAM file correctly
     @Test()
diff --git a/java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleTest.java b/java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleUnitTest.java
similarity index 96%
rename from java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleTest.java
rename to java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleUnitTest.java
index ce73103e8..9daa55a96 100644
--- a/java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleTest.java
+++ b/java/test/org/broadinstitute/sting/gatk/datasources/sample/SampleUnitTest.java
@@ -11,7 +11,7 @@ import org.junit.Test;
  * Date: Sep 9, 2010
  * Time: 8:21:00 AM
  */
-public class SampleTest extends BaseTest {
+public class SampleUnitTest extends BaseTest {
 
     static Sample sampleA;
     static Sample sampleA1;