Index: applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/OsmFileCacheTileLoader.java
===================================================================
--- applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/OsmFileCacheTileLoader.java	(revision 16399)
+++ applications/viewer/jmapviewer/src/org/openstreetmap/gui/jmapviewer/OsmFileCacheTileLoader.java	(revision 16768)
@@ -56,4 +56,5 @@
         super(map);
         String tempDir = System.getProperty("java.io.tmpdir");
+        String userName = System.getProperty("user.name");
         try {
             if (cacheDir == null) {
@@ -61,5 +62,10 @@
                     throw new IOException("No temp directory set");
                 }
-                cacheDir = new File(tempDir, "JMapViewerTiles");
+                String subDirName = "JMapViewerTiles";
+                // On Linux/Unix systems we do not have a per user tmp directory. 
+                // Therefore we add the user name for getting a unique dir name.  
+                if (userName != null && userName.length() > 0)
+                    subDirName += "_" + userName;
+                cacheDir = new File(tempDir, subDirName);
             }
             log.finest("Tile cache directory: " + cacheDir);
@@ -72,5 +78,5 @@
         }
     }
-    
+
     /**
      * Create a OSMFileCacheTileLoader with system property temp dir.