diff --git a/GPy/core/parameterization/array_core.py b/GPy/core/parameterization/array_core.py
index e5b2ac07..a338ceed 100644
--- a/GPy/core/parameterization/array_core.py
+++ b/GPy/core/parameterization/array_core.py
@@ -4,7 +4,7 @@
 __updated__ = '2013-12-16'
 
 import numpy as np
-from parameter_core import Observable, Parameterizable
+from parameter_core import Observable
 
 class ParamList(list):
     """
diff --git a/GPy/core/parameterization/parameter_core.py b/GPy/core/parameterization/parameter_core.py
index 94567761..6afa94cb 100644
--- a/GPy/core/parameterization/parameter_core.py
+++ b/GPy/core/parameterization/parameter_core.py
@@ -19,12 +19,13 @@ class Observable(object):
         self._observer_callables_[observer].append(callble)
 
     def remove_observer(self, observer, callble=None):
-        if callble is None:
-            del self._observer_callables_[observer]
-        else:
-            self._observer_callables_[observer].remove(callble)
-            if len(self._observer_callables_[observer]) == 0:
-                self.remove_observer(observer)
+        if observer in self._observer_callables_:
+            if callble is None:
+                del self._observer_callables_[observer]
+            elif callble in self._observer_callables_[observer]:
+                self._observer_callables_[observer].remove(callble)
+                if len(self._observer_callables_[observer]) == 0:
+                    self.remove_observer(observer)
 
     def _notify_observers(self):
         [[callble(self) for callble in callables]
diff --git a/GPy/util/caching.py b/GPy/util/caching.py
index 47a44d58..8e60cf26 100644
--- a/GPy/util/caching.py
+++ b/GPy/util/caching.py
@@ -19,8 +19,9 @@ class Cacher(object):
         for a in ca:
             if (not any(a is ai for ai in cached_args)) and a is not None:
                 cached_args.append(a)
-
         if not all([isinstance(arg, Observable) for arg in cached_args]):
+            print cached_args
+            import ipdb;ipdb.set_trace()
             return self.operation(*args)
         
         if cached_args in self.cached_inputs:
@@ -46,6 +47,7 @@ class Cacher(object):
         self.inputs_changed = [any([a is arg for a in args]) or old_ic for args, old_ic in zip(self.cached_inputs, self.inputs_changed)]
 
     def reset(self, obj):
+        [[a.remove_observer(self, self.on_cache_changed) for a in args] for args in self.cached_inputs]
         [[a.remove_observer(self, self.reset) for a in args] for args in self.cached_inputs]
         self.cached_inputs = []
         self.cached_outputs = []