Can't share isolated storage file between applications in different app pools

[FoadT]

I've got various web apps (containing WCF services) in IIS under the default website. As long as they are all running in the same app pool they can access a shared isolated storage file no problem.However, once I move them to different app pools I get "System.IO.IsolatedStorage.IsolatedStorageException: Unable to create mutex" when one tries to access a file created by another. They are all running under NetworkService user. I tried GetUserStoreForAssembly and GetMachineStoreForAssembly all with the same result. Any ideas why they couldn't use a shared file?I made sure to close the stream and even dispose it in case one was holding onto it, but I am running a simple test where one service writes it, then another tries to read from it later, and it always fails.Also, I am accessing the isolated store from a signed assembly.Does anybody have any ideas?Here is the code:\[code\]Private Sub LoadData() Dim filename = FullFilePath(_fileName) Dim isoStorage As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForAssembly() ' Tried GetMachineStoreForAssembly, same failure isoStorage.CreateDirectory(ROOT_DIRECTORY) If (isoStorage.GetFileNames(filename).Length = 0) Then Return End If Dim stream As Stream = New IsolatedStorageFileStream(filename, FileMode.OpenOrCreate, isoStorage) If stream IsNot Nothing Then Try Dim formatter As IFormatter = New BinaryFormatter() Dim appData As Hashtable = DirectCast(formatter.Deserialize(stream), Hashtable) Dim enumerator As IDictionaryEnumerator = appData.GetEnumerator() While enumerator.MoveNext() Me(enumerator.Key) = enumerator.Value End While Finally stream.Close() stream.Dispose() stream = Nothing End Try End IfEnd SubPublic Sub Save() Dim filename = FullFilePath(_fileName) ' Open the stream from the IsolatedStorage. Dim isoFile As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForAssembly() ' Tried GetMachineStoreForAssembly, same failure Dim stream As Stream = New IsolatedStorageFileStream(filename, FileMode.Create, isoFile) If stream IsNot Nothing Then Try Dim formatter As IFormatter = New BinaryFormatter() formatter.Serialize(stream, DirectCast(Me, Hashtable)) Finally stream.Close() stream.Dispose() stream = Nothing End Try End IfEnd Sub\[/code\]