Problem
At a customer site that had critical updates to install on a few of their servers. When we attempted to download the updates we found that the download status bar would get stuck and not download:

We looked into the windowsupdate.log in the root of the Windows directory and found a lot of messages that related to the BIT (Background Intelligent Transfer) service:
2011-02-06 20:24:17:829 864 124c DnldMgr WARNING: Suspend failed with 0×80200002. Continuing.
2011-02-06 20:24:18:204 10136 22ec COMAPI >>– RESUMED — COMAPI: Download [ClientId = WindowsUpdate]
2011-02-06 20:24:18:204 10136 22ec COMAPI – WARNING: Download call aborted
2011-02-06 20:24:18:204 10136 22ec COMAPI – WARNING: Exit code = 0x80240FFF; Call error code = 0x8024000B
Resolution
After a bit of researching we found a very useful tool that is part of the Windows 2003 Support Tools pack:
http://www.microsoft.com/downloads/en/details.aspx?FamilyID=96a35011-fd83-419d-939b-9a772ea2df90&displaylang=en
The name of the utility is bitsadmin. This command line utility gives you control over the BIT’s jobs that are running such as the Windows updates.
First download both the msi and the cab file to the same folder, then run the msi file to install them (The download above will work on both 32 and 64 bit systems). Once installed go to the Start Menu –> Windows Support Tools –> Command Prompt
In the command prompt run the following command to see what jobs may be stuck:
bitsadmin /list /allusers
You will see an output similar to this:

What we need to do is kill off all of the jobs that are suspended and get Windows Update to start from scratch. To kill off the list of jobs put in the following command line:
bitsadmin /reset /allusers
As we want the Windows Updates to start from scratch it is also a good idea to delete the contents of the following folder:
C:\WINDOWS\SoftwareDistribution\Download
After you have done this re-launch Windows Update and the updates should download and install without any issues.
Summary
1. Run bitsadmin /list /allusers to see if there are any BITs jobs stuck (If not there download and install Windows Support Tools)
2. Run bitsadmin /reset /allusers to kill off all BITs jobs
3. Clear out contents of directory C:\WINDOWS\SoftwareDistribution\Download
4. Re-run the Windows Update Client