SEATTLE - Microsoft Corp. acknowledged Wednesday that it needs to better inform users that its tool for determining whether a computer is running a pirated copy of Windows also quietly checks in daily with the software maker. The company said the undisclosed daily check is a safety measure designed to allow the tool, called Windows Genuine Advantage, to quickly shut down in case of a malfunction. For example, if the company suddenly started seeing a rash of reports that Windows copies were pirated, it might want to shut down the program to make sure it wasn't delivering false results. "It's...