I have the same problem. I even went back and reinstalled all the old versions... what a mess.. still no positive results.
ADE requires Microsoft .Net 3.5 when installing version 1.8 or higher. I'm using windows 8 and have successfully gotten 126.96.36.1991 to run. You'll have to pull it off a download site like windows9.com. I assume 2.0 will be updated soon enough to use .Net 4.0.
I would not assume anything. Part of my frustration with ADE is that
changes take an ice age to be rolled out. ADE 2.0 was in Beta for more
than six months that I know of, and does not address some of the
hardware/software issues that are over a year old.
I had installation problems with ADE 2 due to using an older AMD processor. After several tries at Chat I was given a link to ADE 1.7. Here it is:
Many thanks, that link is really helpful.
Now at least I can use ADE 1.7 while waiting for ADE 2.1 for Win8.
Windows Update will not install .NET 3.5 for you.
Use Control Panel -> Programs -> "Turn Windows features on or off". You should see .NET 3.5 as the first thing in that list. Select it and click OK. It will install .NET 3.5.
You should be able to install ADE 2 after that.