This is what worked for me I have XP
1. Open Run, and type in services.msc then press Enter. Alternatively, go to Control Panel -> Administrator Tools -> Services.
2. Locate Windows Installer in the all install services listing.
3. Verify that the Status is Started. If the Status column is blank, right click on Windows Installer and select Start.
4. If you get error trying to force start the Windows Installer service, try to change the Startup Type to Automatic (default is Manual), and then restart the computer.
The above steps can also be performed via MSConfig to set Windows Installer service to auto start on boot up.