I would try to reinstall it again.
Check the readme file, and follow the step by step instructions, be sure to CHMOD the files to file permission the readme file asks.
It seems it can't open the lang-.php file, have you included one on the right directory?
I installed one the the PHPnuke, the first time it showed a lot of errors, I had to reinstall it and then it seemed ok but new errors appeared.
There are other cool php portals check this site
http://php.resourceindex.com or
www.hotscripts.comPersonnally I don't like pre-made portals, of course it is faster than creating your one portal in php but i prefer that, I create my own haeder e footer files, voting polls, news system and mailing lists and it comes out the way I like.
I'm sorry but it is all the help I can give you, it's hard to understand the problem and to explain it online.