Free PHP/mySQL Chat Program (that works)

Ok .... I have played the configure, upload, set permissions, and watch the 500 errors fly Game..... I do not think I am a moron but perhaps this is the case.. I was wondering if anyone out there has managed to come up with a free chat script that works and a free forum script that works.

I have tried many that supposivly works.. and I have managed to get XMB to work on another account of mine (unfortunatly the original install file was lost on my drive and now the co that makes it is charging

SO what I am looking for is a script that can work with 755 permissions.

it seems that all the others need 766 or 777
please help me by providing a link to the download files and an example of it being impplemented would be really great.

Thank you