Expiration of Service Pack Blocker Tool for Windows Vista & Windows XP
Expiration of Service Pack Blocker Tool for Windows Vista & Windows XP
Posted: 29 Jan 2009
I have some important information for those of you who have installed the Service Pack Blocker Tool for Windows XP or Windows Vista. The Service Pack Blocker Tool temporarily prevents the installation of a service pack through Windows Update, typically for one year after general availability of the service pack. We are announcing the upcoming expiration dates for the Service Pack Blocker Tool for Windows Vista SP1 and Windows XP SP3:
Windows Vista SP1: April 28, 2009
Windows XP SP3: May 19, 2009
After April 28th, Windows Vista SP1 will be delivered via Windows Update. And after May 19th, Windows XP SP3 will also be delivered via Windows Update. 
For more information on the Service Pack Blocker Tool, please see this Q&A.
The service packs (SP1 for 7 and SP2 for Vista) have been approved for install. Clients just don't detect that SPs being available on the server.
I ran WSUS Detection tool from Microsoft and it said 'passed' and clients are able to contact WSUS Server.
Help?
Source -
Microsoft releases service pack blocker for Windows 7 SP1
Same topic, different source -
Bink.nu | Windows 7 Service Pack Blocker Tool Kit - Bink.nu