I have the following problem:
When trying to upload ANY FILE trough the html editor after choosing to upload new file I'm getting the document manager window but there are no files or folder visible (as if the site is empty) and it is impossible to upload file (to the root directory).
This happens with all of the html editors (RAD, Telerik, cskeditor) apart of the old fckeditor that has no problem uploading files (but has few others).
I don't have any problem uploading files with the file manager and I do all the editing under administrator role (that says, i think, it's not permission problem).

I've looked into the event log and got the following error message:

RawURL: /Providers/HtmlEditorProviders/Telerik/Telerik.Web.UI.DialogHandler.aspx?tabid=56&language=he-IL&DialogName=DocumentManager&Skin=Vista&Title=Document+Manager&doid=0775d6e5-3d4c-4385-8250-6b26befa690d&dpptn=&rwndrnd=0.9713753666098587

AbsoluteURL: /Providers/HtmlEditorProviders/Telerik/Telerik.Web.UI.DialogHandler.aspx

AbsoluteURLReferrer: http://www.ihaklai.org.il/Providers/HtmlEditorProviders/Telerik/Telerik.Web.UI.DialogHandler.aspx?tabid=56&language=he-IL&DialogName=DocumentManager&Skin=Vista&Title=Document%20Manager&doid=0775d6e5-3d4c-4385-8250-6b26befa690d&dpptn=&rwndrnd=0.9713753666098587

UserAgent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:14.0) Gecko/20100101 Firefox/14.0.1

DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider

ExceptionGUID: faad6dd9-b32b-4f48-8e57-e9ab0a58226c

InnerException: Unable to complete operation. An unknown error occurred. Portal Root

FileName:

FileLineNumber: 0

FileColumnNumber: 0

Method: System.ThrowHelper.ThrowArgumentException

StackTrace:

Message: DotNetNuke.HtmlEditor.TelerikEditorProvider.FileManagerException: Unable to complete operation. An unknown error occurred. Portal Root ---> System.ArgumentException: An item with the same key has already been added. at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value) at DotNetNuke.HtmlEditor.TelerikEditorProvider.FileSystemValidation.get_UserFolders() at DotNetNuke.HtmlEditor.TelerikEditorProvider.FileSystemValidation.GetUserFolder(String path) at DotNetNuke.HtmlEditor.TelerikEditorProvider.PortalContentProvider.AddChildDirectoriesToList(DirectoryItem[]& radDirectories, Boolean recursive, Boolean loadFiles) at DotNetNuke.HtmlEditor.TelerikEditorProvider.PortalContentProvider.GetDirectoryItemWithDNNPermissions(String path, Boolean loadFiles) at DotNetNuke.HtmlEditor.TelerikEditorProvider.PortalContentProvider.ResolveRootDirectoryAsTree(String path) --- End of inner exception stack trace

Please HELP...THX