Software updates failing on some clients

I have deployed a package of over 160 Microsoft Updates to about 900 machines.  It has been going swimmingly with the occasional straggler.  I have been noticing this trend of some clients not installing some of the updates and showing non-compliant.  These upates had no problem installing on about 880 other machines and it's got me beating my head against a wall.  Does anyone have any ideas?

The significant entries in the WUAHandler.log file read:

Could not find update (df4711b7-174e-4248-8044-b7b6c3feaa3a:100) in any of the registered update sources, skipping.
No updates were actionable for installation.

UpdatesHandler.log:

No need to install update (df4711b7-174e-4248-8044-b7b6c3feaa3a) as it is no more missing
Update (df4711b7-174e-4248-8044-b7b6c3feaa3a) execution completed with state COMPLETE_NO_REBOOT.

Raising event:
[SMS_CodePage(437), SMS_LocaleID(1033)]
instance of SMS_SUMAgentUpdateError_Internal
{
 ClientID = "GUID:EA586D6E-F836-499B-8942-66CAD5C25E45";
 DateTime = "20091217144701.720000+000";
 MachineName = "1826-2FLR-D023";
 ModelName = "Site_906E2D61-056B-4802-AF31-55D7B8155134/SUM_df4711b7-174e-4248-8044-b7b6c3feaa3a";
 ProcessID = 484;
 SdmPackageVersion = "1";
 SiteCode = "PU3";
 ThreadID = 3468;
 UpdateId = "df4711b7-174e-4248-8044-b7b6c3feaa3a";
 Win32ErrorCode = 2147747432;
};

These machines have installed MANY other updates with no problems.  Any ideas?