I don't know what this error means. Could someone shed a light on this please? 

When I remove a user from our intranet I unauthorize them first, then delete the unauthorized user, and finally permanently delete them. In all, everything appears to be ok because the user was removed from all the tables, But errors I'm not familiar with always concern me. Thanks in advance for your help.

Error: User Accounts is currently unavailable. DotNetNuke.Services.Exceptions.ModuleLoadException: The directory is not empty. ---> System.IO.IOException: The directory is not empty.

at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) at System.IO.Directory.DeleteHelper(String fullPath, String userPath, Boolean recursive, Boolean throwOnTopLevelDirectoryNotFound) at System.IO.Directory.Delete(String fullPath, String userPath, Boolean recursive, Boolean checkHost) at DotNetNuke.Services.FileSystem.FolderManager.DeleteFolderInternal(IFolderInfo folder, Boolean isCascadeDeleting) at DotNetNuke.Services.FileSystem.FolderManager.DeleteFolderRecursive(IFolderInfo folder, ICollection`1 notDeletedSubfolders, Boolean isRecursiveDeletionFolder, Boolean unmap) at DotNetNuke.Services.FileSystem.FolderManager.DeleteFolder(IFolderInfo folder, ICollection`1 notDeletedSubfolders) at DotNetNuke.Entities.Users.UserController.RemoveUser(UserInfo user) at DotNetNuke.Modules.Admin.Users.UserAccounts.RemoveUser(Int32 userId) --- End of inner exception stack trace ---