you were right, I deleted all files in /forums and reloaded them. Now I come some steps further ending with following error message:
MySQL error reported!
Query: SELECT cpaccess,modaccess,diskspace,uploadsize,uploads,comments,editpho,editposts,useralbums,reqmod,canassign FROM ppusergroups WHERE groupid=99 LIMIT 1
Result: Unknown column 'reqmod' in 'field list'
Database handle: Resource id #1
how to preceed here?