Transfers data between clients and servers in the background. If BITS is disabled, features such as Windows Update will not work correctly.
Background Intelligent Transfer Service is a Win32 service. In Windows XP it won't start until the current user starts it. When the Background Intelligent Transfer Service is started, it is running as LocalSystem in a shared process of svchost.exe. Other services and drivers are allowed to run in the same process. If the Background Intelligent Transfer Service fails to start, the technical information about the error is added to the Event Log. Windows XP startup should proceed, but a message box should be displayed informing the user that the BITS service has failed to start.
The BITS service is using the qmgr.dll file that is located in the %WinDir%\system32 folder. If the file is changed, damaged or deleted, you can restore its original version from Windows XP installation media.