You may see the following errors in the cas.log and contenttransfermanager.log:
CAS.Log:
Download completed for content PackageGUID.X under context System 3/25/2010 12:31:21 AM 2096 (0x0830)
Failed to instantiate UI Server {SOMEGUID1} with error 8000401a 3/25/2010 12:31:21 AM 2096 (0x0830)
Failed to instantiate UI Server 2 {SOMEGUID2} with error 8000401a 3/25/2010 12:31:21 AM 2096 (0x0830)
Failed to instantiate Updates UI Server {SOMEGUID3} with error 8000401a 3/25/2010 12:31:21 AM 2096 (0x0830)
Failed to instantiate VApp UI Server {SOMEGUID4} with error 0x8000401A 3/25/2010 12:31:21 AM 2096 (0x0830)
There are 0 files in the directory compared to 1 expected files 3/25/2010 12:31:21 AM 2096 (0x0830)
Hash does not match expected <Content ContentId="PackageGUID" Version="X"><FileContent Name="Package Name" Hash="SomeHashValuenumber" HashAlgorithm="SHA1" Size="513400"/></Content>, actual 3/25/2010 12:31:21 AM 2096 (0x0830)
Hash matching failed. 3/25/2010 12:31:21 AM 2096 (0x0830)
Download failed for content PackageGUID.X under context System, error 0x80091007 3/25/2010 12:31:21 AM 2096 (0x0830)
So it thinks it downloaded, but it really did not, and the clients cache is not populated with the package id named folder, so this explains why the hash mismatch occurs.
ContentTransferManager.log:
CTM job {SOMEGUID} successfully processed download completion. 3/25/2010 12:31:34 AM 3500 (0x0DAC)
CTM encountered error processing reply from DTS. Code 0x80040215 3/25/2010 12:33:06 AM 3084 (0x0C0C)
So it actually showed a download complete, then it gave the error above.