Windows 7: Windows Installer Service problems

After downloading an update for the latest version of Itunes, I keep getting a message saying 'Windows Installer Service' could not be accessed. I have checked that the Windows Installer is running and that I am not in 'Safe Mode'. Often (but not always) the Installer shuts down some time during the download. I have tried with Installer set to Manual and also to Auto but I still keep getting the same message. Any help would be much appreciated.

Welcome to Seven Forums Mark Riley. Try this 1st:

Start> In search box type cmd> Right click on cmd.exe in results above and choose Run as administrator> When the command prompt opens, type:

MSIEXEC /UNREGISTER

Enter

MSIEXEC /REGSERVER

Enter

See if that helps. If not, I'd try running the System File Checker

SFC /SCANNOW Command - System File Checker

A Guy