[kh99]

Well, assuming that the problem is config.php (and that you're using a Windows computer at home or wherever you are). You would want to:

1) Download and install notepad++ (http://notepad-plus-plus.org)
2) Download config.php from your forum
3) open config.php in notepad++, and under the Encoding menu, choose "Encode in UTF-8 without BOM".
4) Save the file and upload it to your forum, overwriting the original.

You won't see the BOM because the editor hides it, so you won't really be making any changes, just open it in the editor, change the encoding, and save it again.