The issue is one where if you have System Center Configuration Manager 2007 running on Windows Server 2008 R2 with WEBDAV 7.5, clients doing downloads using BITS can either appear to hang or they may just take a very long time downloading updates when your package contains many folders and files.
Latest SCCM CB Package Download Issues? SCCM Troubleshooting Steps With Flowcharts – Anoopcnair.com
I have gone through a good post on The Configuration Manager Support Team Blog
