It's a known bug with PyPy support in PyCharm, see http://youtrack.jetbrains.com/issue/PY-9546.
The bug seems to be fixed now.
Question
For some weird reason, my PyCharm loves to show unresolved errors everywhere.
But only with pypy. The source runs just fine, even PyCharm can run the code perfect.
But the red lines everywhere are really annoying.
The problem:
Ps.: I tried the Invalidate cache method, but it didn't help.
Solution
It's a known bug with PyPy support in PyCharm, see http://youtrack.jetbrains.com/issue/PY-9546.
The bug seems to be fixed now.