Further on this topic. It seems that there is some incompatibility somehow.
According to these pages where the same error was reported to occurr in other applications
https://sourceware.org/bugzilla/show_bug.cgi?id=11051
http://www.esrf.eu/mail_archives/tango/archive/msg04341.html
the error appears because the boost was compiled with a python interpreter that set Py_UNICODE_SIZE to 2,
while evidently the version installed in my computer (python2.7.6) has the above macro set to 4. I installed Ubuntu 14.04 less than a month ago, so this must be some recent settings.
I am wondering if there is a way to get around this problem.