The test_installer step is failing on LUCI on "Win7 Tests (1)"

I've done some debugging and found that it can't figure out how to uninstall chrome on a system level once it installs it. You can see this in https://luci-milo.appspot.com/p/chromium/builders/luci.chromium.ci/Win7%20Tests%20%281%29/142

Subsequent builds fail because chrome was never uninstalled on the machine. It tries to run a test to install chrome on a per user basis and fails, because it tries to verify that chrome isn't installed on a system level, and it is, because the previous test failed.

It seems like there should be a step at the beginning of the test to make sure chromium isn't installed anywhere on the bots, so that we start at a known state every time, but maybe I don't understand how the test works.

Anyways, it seems that the chrome install step is failing somehow; the error when running the uninstall_chrome.py script I get (and the build gets) is:

KeyError: 'Registry key HKEY_LOCAL_MACHINE\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\Chromium is missing'

I looked at the registry on that machine, and that key really is missing. There's a node which looks like it could replace that, but it has Wow6432Node in the name; I have no idea what that means.

The machines seem to be for all intents and purposes identical; they're both Windows 7 SP1, with similar RAM and CPU. My guess is that the old machine has been running long enough that something changed about how we image windows 7 machines, and that is causing issues on the new one. Labs, any ideas here?

Test installer people, do you have any idea why this could be happening? Would definitely appreciate some help here. Not sure if these are the right components, feel free to re-route.