On some further examination of the code, I've had a couple more ideas:
Check in your moodle config.php file that the line...
$CFG->dirroot = '/path/to/moodle/code/dir';... has the correct path to your moodle source code directory.
- Also check the permissions, to make sure that the eportfolio directory and all of its files are accessible by the web server.
However, I would have expected more things to break than just this bug if either of the two above were not set up correctly. Again, it might be worth checking though