Hi 
Revouninstaller usually does a good job of finding all the stray
bits&bobs Windows scatters around it's system. It gives you a choice
as to whether you want to remove those odd bits of strangeness. I
haven't used it many times so i can't reliably recommend it but it's
been brilliant the few times i have used it and a few other people oin
this mailing list spoke of it quite highly too.
Unfortunately it is not free, but luckily does have a 30day free trial;
http://www.revouninstaller.com/
I try to avoid using it on a machine untill it really needs it because
i am never sure if i will ever be able to use it a 2nd time. However
it sounds like you might have reached that point already.
So it might be worth trying to do a "parallel install" first just to
see if that can be done. This is probably a lot easier to try than it
sounds but i haven't tried it myself yet.
https://wiki.documentfoundation.org/Installing_in_parallel/Windows
Regards from
Tom 