Every second or third time I click on link within the module ( it doesnt seem to matter which one) it goes to a blank screen. I turned on debugging and this is what it says:

Fatal error: Class 'portfolio_module_caller_base' not found in /home/mysite/public_html/moodle/mod/data/locallib.php on line 29

Posted in database module forum. Penny Leach replied:

It looks to me like that file is missing a require_once($CFG->libdir . '/portfolio/caller.php'); at the top. Can you file a bug in the tracker to that effect?