The Windows Installer is the program that is used when installing new software on your Microsoft operating system. It is an integral part of the system, and without it, simple procedures can become much more tedious.

So what does it do? The Installer exists to transfer new files in to a workable directory. It also writes to the Windows registry and performs basic edits and deletes on command of the installed software. Upon running the utility, you’ll be asked to agree with the software licenser’s terms and conditions, digitally sign a couple of boxes and select where you wish said software to be installed.

As you can probably imagine, a problem with Windows Installer is likely to throw a major spanner in to your works. Not only is it used to install software, but it’s used to uninstall it too. Whenever you go to an Uninstall link in the Start bar, for example, you’re making use of the Windows Installer. There are other ways to remove programs, but this is by far the most convenient.

If Windows Installer becomes corrupt or begins to return errors, you should consider repairing it through a re-install, or manual editing of its permissions. Some computer cleaning utilities make the job a lot easier and it’s quite possible to save hours on end by downloading one and putting it to scan your system. This will often correct any faults that might have been leading to a non-working Installer.

Sometimes it’s necessary to go in and edit the actual permissions of the program.

"Could not start the Windows Installer service on Local Computer. Error: Access is denied."

If you receive this error, check that the environment of the installer is written with a correct path. Also make sure that the variable permissions are set to execute at 255 characters. This will usually clear up any access errors.

If you receive different more general errors such as “Windows Installer Service couldn’t be started", it’s hard to pin exactly where the program has become corrupt. Sometimes it could even be the software package itself. If you’re having problems with more than one installation package, it might be worth reinstalling the actual Windows Installer.

To do this, follow the steps below:

• Go to Start and then Run.
• Type “msiexec /unreg” and press Enter to uninstall the Installer.
• Go back to Start and Run.
• Type “msiexec /regserver” and press Enter to re-install.
• It may be necessary to restart your computer.

If you are still faced with difficulties getting the Windows Installer to operate, the next big possibility is that you’ve contracted a virus – and a pretty damaging one at that.

Whip out your anti-Virus protection suite of choice and run a full scan of the local system. Gather together all the bad files and wipe them completely off your system. If you’re harbouring one of the less deadly viruses, this might be enough to solve the problem. If the virus is damaging enough to attack the shell, you should consider a visit to the nearest repair store.

It’s unlikely that you’d be suffering from a virus and the Windows Installer would be the only affected program – but it’s entirely possible. Run a thorough check and quarantine any files that might be de-stabilising your system.

It’s often a good idea to re-install the Windows Installer AFTER you’ve cleaned the drive of viruses and malware. That way, the virus can’t attack the re-installation process and you’re more likely to avoid a corrupted file.