diff --git a/mozilla/netwerk/cache/src/nsCacheService.cpp b/mozilla/netwerk/cache/src/nsCacheService.cpp
index 25710ba6589..b5cb4ef68c2 100644
--- a/mozilla/netwerk/cache/src/nsCacheService.cpp
+++ b/mozilla/netwerk/cache/src/nsCacheService.cpp
@@ -433,7 +433,13 @@ nsCacheService::CreateDiskDevice()
 
     nsresult rv = mDiskDevice->Init();
     if (NS_FAILED(rv)) {
-        // XXX log error
+#if DEBUG
+        printf("###\n");
+        printf("### mDiskDevice->Init() failed (0x%.8x)\n", rv);
+        printf("###    - disabling disk cache for this session.\n");
+        printf("###\n");
+#endif        
+        mEnableDiskDevice = PR_FALSE;
         delete mDiskDevice;
         mDiskDevice = nsnull;
     }
@@ -732,28 +738,36 @@ nsCacheService::EnsureEntryHasDevice(nsCacheEntry * entry)
 {
     nsCacheDevice * device = entry->CacheDevice();
     if (device)  return device;
+    nsresult rv = NS_OK;
 
     if (entry->IsStreamData() && entry->IsAllowedOnDisk() && mEnableDiskDevice) {
         // this is the default
         if (!mDiskDevice) {
-            nsresult rv = CreateDiskDevice();
-            if (NS_FAILED(rv))
-                return nsnull;
+            rv = CreateDiskDevice();  // ignore the error (check for mDiskDevice instead)
         }
 
-        device = mDiskDevice;
-    } else if (mEnableMemoryDevice) {
+        if (mDiskDevice) {
+            entry->MarkBinding();  // XXX
+            rv = mDiskDevice->BindEntry(entry);
+            entry->ClearBinding(); // XXX
+            if (NS_SUCCEEDED(rv))
+                device = mDiskDevice;
+        }
+    }
+     
+    // if we can't use mDiskDevice, try mMemoryDevice
+    if (!device && mEnableMemoryDevice) {
         NS_ASSERTION(entry->IsAllowedInMemory(), "oops.. bad flags");
-        device = mMemoryDevice;
+        
+        entry->MarkBinding();  // XXX
+        rv = mMemoryDevice->BindEntry(entry);
+        entry->ClearBinding(); // XXX
+        if (NS_SUCCEEDED(rv))
+            device = mMemoryDevice;
     }
 
     if (device == nsnull)  return nsnull;
 
-	entry->MarkBinding(); // XXX
-    nsresult  rv = device->BindEntry(entry);
-    entry->ClearBinding(); // XXX
-    if (NS_FAILED(rv)) return nsnull;
-
     entry->SetCacheDevice(device);
     return device;
 }
diff --git a/mozilla/netwerk/cache/src/nsDiskCacheDevice.cpp b/mozilla/netwerk/cache/src/nsDiskCacheDevice.cpp
index 8cd008f8ed4..f51103c6c93 100644
--- a/mozilla/netwerk/cache/src/nsDiskCacheDevice.cpp
+++ b/mozilla/netwerk/cache/src/nsDiskCacheDevice.cpp
@@ -633,6 +633,14 @@ nsDiskCacheDevice::Init()
     gFileTransportService = do_GetService("@mozilla.org/network/file-transport-service;1", &rv);
     if (NS_FAILED(rv)) return rv;
     
+    // delete "Cache.Trash" folder
+    nsCOMPtr<nsIFile> cacheTrashDir;
+    rv = mCacheDirectory->Clone(getter_AddRefs(cacheTrashDir));
+    if (NS_FAILED(rv))  return rv;
+    rv = cacheTrashDir->SetLeafName("Cache.Trash");
+    if (NS_FAILED(rv))  return rv;
+    (void) cacheTrashDir->Delete(PR_TRUE);  // ignore errors, we tried...
+
     // XXX read in persistent information about the cache. this can fail, if
     // no cache directory has ever existed before.
     rv = readCacheMap();
@@ -1502,7 +1510,45 @@ nsresult nsDiskCacheDevice::clobberDiskCache()
     
     // recursively delete the disk cache directory.
     rv = mCacheDirectory->Delete(PR_TRUE);
-    if (NS_FAILED(rv)) return rv;
+    if (NS_FAILED(rv)) {
+        // try moving it aside
+        
+        // get parent directory of cache directory
+        nsCOMPtr<nsIFile> cacheParentDir;
+        rv = mCacheDirectory->GetParent(getter_AddRefs(cacheParentDir));
+        if (NS_FAILED(rv))  return rv;
+        
+        // create "Cache.Trash" directory if necessary
+        nsCOMPtr<nsIFile> oldCacheDir;
+        rv = cacheParentDir->Clone(getter_AddRefs(oldCacheDir));
+        if (NS_FAILED(rv))  return rv;
+        rv = oldCacheDir->Append("Cache.Trash");
+        if (NS_FAILED(rv))  return rv;
+        
+        PRBool exists = PR_FALSE;
+        rv = oldCacheDir->Exists(&exists);
+        if (NS_FAILED(rv))  return rv;
+        
+        if (!exists) {
+            // create the "Cache.Trash" directory
+            rv = oldCacheDir->Create(nsIFile::DIRECTORY_TYPE,0777);
+            if (NS_FAILED(rv))  return rv;
+        }
+        
+        // create a directory with unique name to contain existing cache directory
+        rv = oldCacheDir->Append("Cache");
+        if (NS_FAILED(rv))  return rv;
+        rv = oldCacheDir->CreateUnique(nsnull,nsIFile::DIRECTORY_TYPE, 0777); 
+        if (NS_FAILED(rv))  return rv;
+        
+        // move existing cache directory into profileDir/Cache.Trash/CacheUnique
+        nsCOMPtr<nsIFile> existingCacheDir;
+        rv = mCacheDirectory->Clone(getter_AddRefs(existingCacheDir));
+        if (NS_FAILED(rv))  return rv;
+        rv = existingCacheDir->MoveTo(oldCacheDir, nsnull);
+        if (NS_FAILED(rv))  return rv;
+    }
+    
     rv = mCacheDirectory->Create(nsIFile::DIRECTORY_TYPE, 0777);
     if (NS_FAILED(rv)) return rv;