I have run into a strange condition on some Windows XP boxes before(imagine that). When I try to install or uninstall anything (including windows updates), I get this error message:
The Windows Installer Service could not be accessed.
This can occur if you are running Windows in safe
mode, or if the Windows Installer is not correctly
installed. Contact your support personnel for assistance.
I don’t have a clue what is causing the Windows Installer Service to not be accessible any longer. However, I have found that the fix is quite easy.
Essentially, you need to be logged in with Administrative privileges and run these two commands from the command line:
This link is the official MS KB article I found this in: