Windows Vista Service Pack 1 (SP1) is not available for installation from Windows Update, and Automatic Updates does not offer Windows Vista SP1 for installation.
This problem occurs because of one or more of the following causes.
You are already running Windows Vista SP1.
Windows Vista SP1 has not been released for the language of the language pack that you have installed.
Windows Service Pack Blocker Tool is used to block the delivery of Windows Vista SP1 from Automatic Updates or from Windows Update.
You tried to install Windows Vista SP1, and the installation failed with a known inconsistency in the file or registry structure.
A hardware device driver or device software was problematic when you updated to Windows Vista SP1.
The Windows Update service can detect the small set of device drivers and software that falls into this category. The Windows Update service will not offer Windows Vista SP1 until an update for the hardware device driver or the device software has been installed.
You have installed a prerelease version of Windows Vista SP1, and you must uninstall the prerelease version, or start with a new installation of Windows Vista.
You used the third-party program vLite to configure the system, and you may have removed required system components that have to be available for Windows Vista SP1 to be installed.
You see one or more updates for Windows Vista when you run Windows Update. However, you do not see Windows Vista SP1 listed.
To resolve this problem, use one or more of the following methods, as appropriate for your situation.
Method for Cause 1
Determine whether you are running Windows Vista SP1. To do this, follow these steps:
Click Start, right-click Computer, and then click Properties.
If Windows Vista SP1 is installed, you will see that a reference to Windows Vista SP1 is displayed at the bottom of the Windows Edition section.
Method for Cause 2
There will be two releases of Windows Vista SP1. The first release of Windows Vista SP1 is available in the following languages:
The second release of Windows Vista SP1 will be available in the remaining 31 languages. The second release of Windows Vista SP1 is scheduled for later in 2008.
You will only be offered Windows Vista SP1 during the first release if your language and any installed language packs are included in the first five languages.
Verify the language and language pack that is installed on your computer.
Method for Cause 3
Windows Service Pack Blocker Tool check here
Method for Cause 4
You may have experienced a known inconsistency in the file system or in the registry for the current set of installed Windows components. If the system has one of a set of repairable inconsistencies, Windows Update will offer an update that will repair this issue. Reopen Windows Update, and then click Check for Updates again.
To do this, follow these steps:
1. Click Start, type Windows Update in the Start Search box, and then press ENTER.
2. Click Check for updates.
If your computer has this known inconsistency, we will now offer an update that will make the correction and that will let Windows Vista SP1 be offered and installed when Windows Update is next checked.
Note For most users, Automatic Update will offer this solution, and then it will re-offer Windows Vista SP1 without any interaction required.
Method for Cause 5
To help ensure a positive update experience, Windows Update will temporarily not offer Windows Vista SP1 to systems that have the following device drivers. In some cases, these device drivers are problematic on Windows Vista-based computers when you update to Windows Vista SP1. By installing updated device drivers, you will resolve the issue and enable Windows Update to offer Windows Vista SP1.
• For x86-based computers: Alcxwdm.sys – version 18.104.22.16842 or earlier
• For x64-based computers: Alcwdm64.sys – version 22.214.171.12442 or earlier
• For x86-based computers: Sthda.sys – version 5.10.5762.0 or earlier
• For x64-based computers: Sthda64.sys – version 5.10.5762.0 or earlier
• For x86-based computers: Stwrt.sys – version 6.10.5511.0 or earlier
• For x64-based computers: Stwrt64.sys – version 6.10.5511.0 or earlier
• For x86-based and x64-based computers: Ctaud2k.sys – version 126.96.36.1992 or earlier
• For x86-based computers: P17.sys – all versions (This was originally a Windows XP-based driver.)
Conexant HD Audio
• For x86-based computers: Chdart.sys – version 188.8.131.52 or earlier
• For x64-based computers: Chdart64.sys – version 184.108.40.206 or earlier
Biometric (Fingerprint) Sensors
• AuthenTec Fingerprint Sensor with the Atswpdrv.sys driver file – version 220.127.116.11 or earlier
• UPEK Fingerprint Sensor with the Tcusb.sys driver file – version 18.104.22.168 or earlier
• For x86-based computers: Igdkmd32.sys – versions between and including driver 22.214.171.1242 and 126.96.36.1993
• For x64-based computers: Igdkmd64.sys – versions between and including driver 188.8.131.522 and 184.108.40.2063
Texas Instruments Smart Card Controller with the GTIPCI21.sys driver file – version 220.127.116.11 or earlier
Sierra Wireless AirCard 580 with the Watcher.exe application – version 18.104.22.168 or earlier (This application is located in the AirCard 580 Program Files folder.)
Symantec software driver for Symantec Endpoint Protection and for Symantec Network Access Control clients
• For x86-based computers: Wgx.sys – versions 11.0.1000.1091 or earlier
• For x64-based computers: Wgx64.sys – versions 11.0.1000.1091 or earlier
Note Symantec is aware of this issue, and it is working on a solution. Symantec provides various update procedures. This includes their LiveUpdate service.
Check here for more solutions