Index: trunk/src/org/openstreetmap/josm/data/Preferences.java
===================================================================
--- trunk/src/org/openstreetmap/josm/data/Preferences.java	(revision 3548)
+++ trunk/src/org/openstreetmap/josm/data/Preferences.java	(revision 3549)
@@ -647,8 +647,8 @@
         for(String k : keys) {
             try {
-              Integer.valueOf(k.substring(l));
-              changed |= put(k, null);
+                Integer.valueOf(k.substring(l));
+                changed |= put(k, null);
             } catch(NumberFormatException e) {
-                e.printStackTrace();
+                /* everything which does not end with a number should not be deleted */
             }
         }
@@ -667,7 +667,8 @@
         for(String k : keys) {
             try {
-              Integer.valueOf(k.substring(l));
-              defaults.remove(k);
+                Integer.valueOf(k.substring(l));
+                defaults.remove(k);
             } catch(Exception e) {
+                /* everything which does not end with a number should not be deleted */
             }
         }