diff --git a/mozilla/netwerk/cache/src/nsCacheService.cpp b/mozilla/netwerk/cache/src/nsCacheService.cpp
index c152d45b016..7aebb3b78a9 100644
--- a/mozilla/netwerk/cache/src/nsCacheService.cpp
+++ b/mozilla/netwerk/cache/src/nsCacheService.cpp
@@ -220,18 +220,15 @@ nsCacheProfilePrefObserver::Observe(nsISupports *     subject,
     } else if (NS_LITERAL_STRING("profile-before-change").Equals(topic)) {
         // profile before change
         mHaveProfile = PR_FALSE;
-        
+
         // XXX shutdown devices
-        if (NS_LITERAL_STRING("shutdown-cleanse").Equals(data)) {
-            // XXX we need to delete the disk cache
-            // printf("cache observer: shutdown-cleanse\n");
-        }
+        nsCacheService::OnProfileShutdown(NS_LITERAL_STRING("shutdown-cleanse").Equals(data));
         
     } else if (NS_LITERAL_STRING("profile-after-change").Equals(topic)) {
         // profile after change
         mHaveProfile = PR_TRUE;
         ReadPrefs();
-        nsCacheService::ProfileChanged();
+        nsCacheService::OnProfileChanged();
     
     } else if (NS_LITERAL_STRING("nsPref:changed").Equals(topic)) {
         if (!mHaveProfile)  return NS_OK;
@@ -317,7 +314,7 @@ nsCacheProfilePrefObserver::ReadPrefs()
         if (directory)
             mDiskCacheParentDirectory = do_QueryInterface(directory, &rv);
     }
-
+    
     // read memory cache device prefs
     rv = prefBranch->GetBoolPref(MEMORY_CACHE_ENABLE_PREF, &mMemoryCacheEnabled);
     if (NS_FAILED(rv)) rv2 = rv;
@@ -1054,21 +1051,59 @@ nsCacheService::ProxyObjectRelease(nsISupports * object, PRThread * thread)
 
 
 void
-nsCacheService::ProfileChanged()
+nsCacheService::OnProfileShutdown(PRBool cleanse)
 {
     if (!gService)  return;
     nsAutoLock lock(gService->mCacheServiceLock);
 
-    NS_ASSERTION(!gService->mDiskDevice, "switching cache directories not supported yet.");
+    if (gService->mDiskDevice) {
+        if (cleanse)
+            gService->mDiskDevice->EvictEntries(nsnull);
+        gService->mDiskDevice->Shutdown();
+        gService->mEnableDiskDevice = PR_FALSE;
+    }
+#if 0
+    if (gService->mMemoryDevice) {
+        gService->mMemoryDevice->Shutdown();
+        gService->mEnableMemoryDevice = PR_FALSE;
+    }
+#endif
+}
 
+
+void
+nsCacheService::OnProfileChanged()
+{
+    if (!gService)  return;
+ 
+    nsresult   rv = NS_OK;
+    nsAutoLock lock(gService->mCacheServiceLock);
+    
     gService->mEnableDiskDevice   = gService->mObserver->DiskCacheEnabled();
     gService->mEnableMemoryDevice = gService->mObserver->MemoryCacheEnabled();
 
-    if (gService->mDiskDevice)
+    if (gService->mDiskDevice) {
+        gService->mDiskDevice->SetCacheParentDirectory(gService->mObserver->DiskCacheParentDirectory());
         gService->mDiskDevice->SetCapacity(gService->mObserver->DiskCacheCapacity());
+
+        // XXX initialization of mDiskDevice could be made lazily, if mEnableDiskDevice is false
+        rv = gService->mDiskDevice->Init();
+        if (NS_FAILED(rv)) {
+            NS_ERROR("nsCacheService::OnProfileChanged: Re-initializing disk device failed");
+            gService->mEnableDiskDevice = PR_FALSE;
+            // XXX delete mDiskDevice?
+        }
+    }
     
-    if (gService->mMemoryDevice)
+    if (gService->mMemoryDevice) {
         gService->mMemoryDevice->SetCapacity(gService->mObserver->MemoryCacheCapacity());
+        rv = gService->mMemoryDevice->Init();
+        if (NS_FAILED(rv) && (rv != NS_ERROR_ALREADY_INITIALIZED)) {
+            NS_ERROR("nsCacheService::OnProfileChanged: Re-initializing disk device failed");
+            gService->mEnableMemoryDevice = PR_FALSE;
+            // XXX delete mMemoryDevice?
+        }
+    }
 }
 
 
diff --git a/mozilla/netwerk/cache/src/nsCacheService.h b/mozilla/netwerk/cache/src/nsCacheService.h
index 886fb60d4fa..43768e83bb5 100644
--- a/mozilla/netwerk/cache/src/nsCacheService.h
+++ b/mozilla/netwerk/cache/src/nsCacheService.h
@@ -112,7 +112,8 @@ public:
     /**
      * Methods called by nsCacheProfilePrefObserver
      */
-    static void      ProfileChanged();
+    static void      OnProfileShutdown(PRBool cleanse);
+    static void      OnProfileChanged();
 
     static void      SetDiskCacheEnabled(PRBool  enabled);
     static void      SetDiskCacheCapacity(PRInt32  capacity);
diff --git a/mozilla/netwerk/cache/src/nsDiskCacheBinding.cpp b/mozilla/netwerk/cache/src/nsDiskCacheBinding.cpp
index df4949521d9..7dd0c2059b8 100644
--- a/mozilla/netwerk/cache/src/nsDiskCacheBinding.cpp
+++ b/mozilla/netwerk/cache/src/nsDiskCacheBinding.cpp
@@ -155,8 +155,7 @@ nsDiskCacheBindery::nsDiskCacheBindery()
 
 nsDiskCacheBindery::~nsDiskCacheBindery()
 {
-    if (initialized)
-        PL_DHashTableFinish(&table);
+    Reset();
 }
 
 
@@ -171,6 +170,15 @@ nsDiskCacheBindery::Init()
     return rv;
 }
 
+void
+nsDiskCacheBindery::Reset()
+{
+    if (initialized) {
+        PL_DHashTableFinish(&table);
+        initialized = PR_FALSE;
+    }
+}
+
 
 nsDiskCacheBinding *
 nsDiskCacheBindery::CreateBinding(nsCacheEntry *       entry,
diff --git a/mozilla/netwerk/cache/src/nsDiskCacheBinding.h b/mozilla/netwerk/cache/src/nsDiskCacheBinding.h
index 8d4a9a5663d..035111e4e37 100644
--- a/mozilla/netwerk/cache/src/nsDiskCacheBinding.h
+++ b/mozilla/netwerk/cache/src/nsDiskCacheBinding.h
@@ -123,6 +123,7 @@ public:
     ~nsDiskCacheBindery();
 
     nsresult                Init();
+    void                    Reset();
 
     nsDiskCacheBinding *   CreateBinding(nsCacheEntry *       entry,
                                          nsDiskCacheRecord *  record);
diff --git a/mozilla/netwerk/cache/src/nsDiskCacheDevice.cpp b/mozilla/netwerk/cache/src/nsDiskCacheDevice.cpp
index d22461b9c21..404b4dcadc1 100644
--- a/mozilla/netwerk/cache/src/nsDiskCacheDevice.cpp
+++ b/mozilla/netwerk/cache/src/nsDiskCacheDevice.cpp
@@ -274,6 +274,8 @@ nsresult
 nsDiskCacheDevice::Init()
 {
     nsresult rv;
+
+    NS_ENSURE_TRUE(!mInitialized, NS_ERROR_FAILURE);
     
     rv = mBindery.Init();
     if (NS_FAILED(rv)) return rv;
@@ -327,6 +329,10 @@ nsDiskCacheDevice::Shutdown()
 
         // write out persistent information about the cache.
         (void) mCacheMap->Close();
+        delete mCacheMap;
+        mCacheMap = nsnull;
+
+        mBindery.Reset();
 
         // no longer initialized.
         mInitialized = PR_FALSE;
@@ -814,13 +820,17 @@ nsDiskCacheDevice::SetCacheParentDirectory(nsILocalFile * parentDir)
 {
     nsresult rv;
     PRBool  exists;
-    NS_ASSERTION(mCacheDirectory == nsnull, "switching cache directories not supportted.");
-    
+
+    if (mInitialized) {
+        NS_ASSERTION(PR_FALSE, "Cannot switch cache directory when initialized");
+        return;
+    }
+
     if (!parentDir) {
         mCacheDirectory = nsnull;
         return;
     }
-    
+
     // ensure parent directory exists
     rv = parentDir->Exists(&exists);
     if (NS_SUCCEEDED(rv) && !exists)
diff --git a/mozilla/netwerk/cache/src/nsMemoryCacheDevice.cpp b/mozilla/netwerk/cache/src/nsMemoryCacheDevice.cpp
index ecd5cf9c955..e9cd9a08e04 100644
--- a/mozilla/netwerk/cache/src/nsMemoryCacheDevice.cpp
+++ b/mozilla/netwerk/cache/src/nsMemoryCacheDevice.cpp
@@ -41,7 +41,8 @@ const char *gMemoryDeviceID      = "memory";
 
 
 nsMemoryCacheDevice::nsMemoryCacheDevice()
-    : mEvictionThreshold(40 * 1024),
+    : mInitialized(PR_FALSE),
+      mEvictionThreshold(40 * 1024),
       mHardLimit(4 * 1024 * 1024),  // set default memory limit, in case prefs aren't available
       mTotalSize(0),
       mInactiveSize(0),
@@ -62,21 +63,25 @@ nsMemoryCacheDevice::~nsMemoryCacheDevice()
 nsresult
 nsMemoryCacheDevice::Init()
 {
-    nsresult  rv;
+    if (mInitialized)  return NS_ERROR_ALREADY_INITIALIZED;
 
-    rv = mMemCacheEntries.Init();
+    nsresult  rv = mMemCacheEntries.Init();
     
     // set some default memory limits, in case prefs aren't available
     mSoftLimit = mHardLimit * 0.9;
 
     // XXX Register as a memory pressure observer
-
+    mInitialized = NS_SUCCEEDED(rv);
     return rv;
 }
 
+
 nsresult
 nsMemoryCacheDevice::Shutdown()
 {
+    NS_ASSERTION(mInitialized, "### attempting to shutdown while not initialized.\n");
+    NS_ENSURE_TRUE(mInitialized, NS_ERROR_NOT_INITIALIZED);
+    
     mMemCacheEntries.Shutdown();
 
     // evict all entries
@@ -107,9 +112,11 @@ nsMemoryCacheDevice::Shutdown()
     NS_ASSERTION(mInactiveSize == 0, "### mem cache leaking entries?\n");
     NS_ASSERTION(mEntryCount == 0, "### mem cache leaking entries?\n");
     
+    mInitialized = PR_FALSE;
     return NS_OK;
 }
 
+
 const char *
 nsMemoryCacheDevice::GetDeviceID()
 {
diff --git a/mozilla/netwerk/cache/src/nsMemoryCacheDevice.h b/mozilla/netwerk/cache/src/nsMemoryCacheDevice.h
index d959af159e5..d6f37056882 100644
--- a/mozilla/netwerk/cache/src/nsMemoryCacheDevice.h
+++ b/mozilla/netwerk/cache/src/nsMemoryCacheDevice.h
@@ -77,6 +77,7 @@ private:
      */
     
     nsCacheEntryHashTable   mMemCacheEntries;
+    PRBool                  mInitialized;
     
     enum { mostLikelyToEvict = 0, leastLikelyToEvict = 1 };   // constants to differentiate eviction lists
     PRCList                 mEvictionList[2];