Windows Installer Cleanup Utility

You'll have to tell us.

The reason that folder is so large is because everything installed with Windows Installer has a full backup (or 2) of its installation files.

Similar goes for the InstallShield installer.

The installer cleanup utility is meant to assist in removing programs that will not uninstall normally. Once the utility is used to remove installation information, the application must be reinstalled.

Installer Cleanup runtime errors I've seen were caused by a corrupt or incompatible version of Windows Installer. Ensure you have the latest versions of both the cleanup utility and Windows Installer (3.1).

The installer folder is usually a few hundred megabytes to several gigabytes in size. I have seen reports of massive installer folders and don't know how they occurred -- possibly multiple installs.

My first thought (which I have not had time to research) is that the C:\Windows\Installer folder and subfolders is a repository for the installer files for your installed software. Much like the cryptically labeled folders in the root of the Windows folder are the uninstall and recovery folders for Windows Updates.

As such, any files you delete from the Installer folder reduce or limit the ability to repair and uninstall some of the software on your system.

Installer cleanup programs remove temp and other leftover files that poorly written installers or crashed installations leave behind.

As to your 40+ GB Installer folder, my first question is how much software have you installed and uninstalled? Or, how many times have you installed Windows over itself on this system or image and had to reinstall your applications over and over again.

All that said, to safely clean out any extra files in the installer folder is going to take some detective work.

It should be safe to remove the installer folder and files for software that is no longer on your computer. (1 that I found on my system was for Acrobat Reader version 6.)

The fun comes in when you have multiple files for the same software package. You need to determine which are still needed. To do so, you need to be able to find and understand the registry keys related to the software package.

As you stated that you are not computer savvy, I recommend that you stay out of the registry. There is just too much risk of causing damage to the registry that could keep your system from booting.

Therefore, unless you really need to free up the disk space, leave the Installer folder as is until the next time you perform a clean install of Windows. When you do so, make sure to delete the installer folder before you start installing Windows.

Chas