The problem occurs on import (import bla reads bla.py), when Python tries to create bla.pyc. The problem is that Python stores the timestamp as 4 bytes in .pyc files, whereas time_t is 64 bits on Windows (at least on Windows XP with Visual Studio).

To support bigger timestamps, we have to change the file format of .pyc files. It cannot be done in Python 2.7, I propose to do it in Python 3.3

See also #5537 and #4379: other issues with 64 bits => 32 bits timestamps.