What is this "Unknown SDK" concept? And some Python weirdness...

I have a ColdFusion project that uses python in its build process. With 122.264 at least, Project Settings > Platform Settings > SDKs > Python 3.1.2 shows the name as Python 3.1.2 and a correct path to python.exe. Below that is a field labeled Unknown SDK Path, whose value is the correct path to python.exe, but it's in red like it's an error.

What does this mean? Is there something I'm supposed to do?

The help btn there opens to "SDKs. Mobile", which I assume isn't relevant,since there's no mobile anything in this project and if there was, it wouldn't be in python.
I've searched the help, but didn't see how to get results more specific than ones containing either "unknown" or "sdk", not helpful. I see this in YouTrack: http://youtrack.jetbrains.com/issue/IDEA-85524, titile "Unknown SDK should be read-only", but that didn't clarify anything for me.


Not sure if this is the same issue or not, but at the bottom of this sceen is a notation that there are two errors, both of which are the following:
"Library 'Python 3.1.2 (path_to_python.exe) interpreter library' has a broken classes path:

Double-clicking the error takes me to  Platform Settings > Global Libraries  > Python 3.1.2, where both the Class and Sources trees show an item in red:
C:\Users\Dave\.IntelliJIdea90\system\python_stubs\1989239741

The .IntelliJIdea90 dir doesn't exist; I have .IntelliJIdea11 and 12, neither of which have a 'python_stubs' dir in system.

I don't work much in python, and I'm afraid I don't remember what I need to do to enable it for a project, if that's what's wrong here, though python support was working when I wrote the existing python code. Do I need to enable it somewhere? Python doesn't show up in Plugins, or in the respository browser. (This is the Ultimate edition.)

It's not completely critical that I get that working right now, since the python code is working fine, but I'd like to get out ahead of this before I really need it, and I'm also wondering if that's related to the Unknown SDK thing above.

Thanks,
Dave