The windows installer service could not be accessed (fixed)

Note: the installer is running fine now, at 10% downloaded, so I think I fixed my own problem. This is for posterity's sake in case anyone else encounters similar problems:

I just tried to install for the first time on Windows Home Premium x64, and got errors saying "The Windows installer service could not be accessed".

After some rooting around, I found references to some .msi installers not checking to see if the installer service was running before trying to access it. Changing the service startup state from "manual" to "automatic" seems to have fixed it.

I got the tip from the following thread on Microsoft technet:

http://social.technet.microsoft.com/Forums/en/w7itproappcompat/thread/eae8a280-8afe-4719-b4c6-98d25a207a6a

I tried a few of the other suggestions in the thread, so I'm not absolutely certain this is what did it, but I'm an experienced software tester (dating back to windows 3.0 days), so I only make one change per attempt and rebooted before & after each change.

None of the things I tried worked, including adding a WOW64 entry to the hkey_current_machine/system/currentcontrolset/services/msiserver entry and setting it to 0 (tried both 1 and 0, neither worked).

It was only after setting the service to "automatic" then rebooting that the installer started running.