Microsoft has released BITS Repair Tool for Windows Vista

The BITS Repair Tool will help you fix a problem caused by the corruption of BITS state files. The problem stops the host process for Windows Services, which prevents you from using BITS to transfer files. Use this tool to resolve the corruption and re-enable BITS transfers. After you install this item, you may have to restart your computer.This update is provided to you and licensed under the Windows Vista License Terms.

Download for 32-bit
Download for 64-bit