PHP infection
 

Hi all, from one day to another my site comes down, I can enter to mi admincp, cPanel and whatever, but my forum is not working.
I search and all the PHP files have this script at the start:

Code:

What can I do? I re-upload all the vB files and some things are correctly working, Im trying now with the hack archives. Is this correct?

Thanks.

PS: My antivirus detect my site.