Analysis Server

We are running Analysis Server on Windows 2000 and it's running under local system account,but most of the time we are getting the following error 'Error = -2147221455 (80040031) Error string: Unable to connect to the registry on the server ,or you are not a member of the OLAP Administrators group on this server.'This happens when we try to refresh the cube and the only thing that makes it work again is to go to the Services under the control panel and stop and restart the OLAP services.I wonder why??By refresh, do you mean re-process the cube?