Yes, this is frustrating a lot of people, and I don’t quite understand why nothing is done about it.
I can’t explain why downgrading to 7.0 shouldn’t work, but I’ve heard others report the same. I can only assume that some bits or pieces of 7.1 are left behind somehow.
It’s worth a try to make an installation using the procedure I explained here, as it makes sure that 7.0 is installed from the beginning, without the downgrade later, which seems to have a better chance at avoiding this issue:
Note: “Expand” the post to see the full explanations with pictures.