Error “the Windows Installer Service Could Not Be Accessed” In Windows Vista

This is a very common issue with Windows Vista because of the recent windows update.

We, normally, face this issue when the Windows Vista is updated to SP2 version.
When you try to install a program which uses Windows Installer in a Windows Vista computer, you may receive the following error.

The Windows Installer Service could not be accessed. This can occur if the Windows Installer is not correctly installed. Contact your support personnel for assistance.

Resolution
Start the Windows Installer service

1. Click Start, type Services.msc and press {ENTER}
2. Double-click Windows Installer
3. Set the Startup type of Windows Installer to Manual
4. Click Start to start the service. Note down the error message if any.
5. Click OK.

If you cannot find the Windows Installer service in Services.msc, then the registry is missing for Windows Installer and we need to fix it.

Steps to fix Windows Installer Service

1. Download msiserver.zip and save it to Desktop.
2. Unzip the file and extract msiserver.reg to the Desktop.
3. Right-click msiserver.reg and choose Merge.
4. Click Yes when asked for confirmation.
5. Restart the System.
6. If you, didn't get the option for Yes, then open Regedit and then Import msiserver.reg file.
7. And, now, restart the System and then, Check under Services.msc, Windows Installer service should be listed now and set the Startup type of Windows Installer to Automatic.
8. Click Start to start the service.

Tried and Tested Solution.