Warning: require(./source/class/class_core.php) [function.require]: failed to open stream: No such file or directory in C:\Program Files\xampps\htdocs\portal.php on line 13

Fatal error: require() [function.require]: Failed opening required './source/class/class_core.php' (include_path='.;C:/Program Files/xampps/htdocs') in C:\Program Files\xampps\htdocs\portal.php on line 13