Question : In Depth of Microsoft Installer's "HKEY_CLASSES_ROOT\Install<wbr />er" Key

I don't really have a problem but I'm just curious on how the Microsoft Installer works. I'm mostly interested in the HKEY_CLASSES_ROOT\Installer key. I know messing with the registry is not a good idea but I'm just curious about all of the keys and values in that key. Are those weird subkeys in HKEY_CLASSES_ROOT\Installer generated randomly? Are they linked to something else in the registry? What are the values in the "Components" subkey for and how do I decode them? How can I tell if one of the subkeys under the "Products" key is invalid? I know this is an extremely difficult topic and Microsoft probably made the key that way on purpose so people don't mess with it. Hopefully someone can help me make more sense of the key. Thanks

Answer : In Depth of Microsoft Installer's "HKEY_CLASSES_ROOT\Install<wbr />er" Key

The key are not randombly created. Are based in a hash, like HKCR\CLSID\ entries

In HKEY_CLASSES_ROOT\Installer\Components there are encoded file asociations and other data to use generally to repair instalations and specially when you open a msi shortcut from start menu.

Check for example the shortcut of Ms Office Word vs the Notepad shortcut. The first is redirected to the msiexec to check if all components are OK and then start the app. Personally I redirect all those shortcuts to the real EXEs, to add performance and to avoid that nag msi repair screens.

I dont know how is encoded the data of msi components

You can clean msi installer keys with Windows Install Clean Up:
http://support.microsoft.com/kb/290301