If your Windows Update is giving problems in Windows or if you find that the Background Intelligent Transfer Service is missing or corrupted, use the BITS Repair Tool from Microsoft to fix the problem.
BITS Repair Tool
The BITS Repair Tool will help you fix a problem caused by the corruption of BITS state files in Windows Vista. If Background Intelligent Transfer Service is missing or corrupted, this tool will help you solve the problem.
The problem stops the host process for Windows Services, which prevents you from using BITS to transfer files.
This Service is required for Windows Updates to run.
So should find that your BITS Service is not functioning properly, use this tool to resolve the corruption and re-enable BITS transfers.
After you install this item, you may have to restart your computer.
You can download BITS Repair Tool from Microsoft.