Hi guys ,
i founded the solution!!!
It wasn't a mime type problem, if so no one php file could be executed.
looking in the apache log files i founded a memory error! infact php has a 8mb memory limit for each script, so load.php , when smf is installed with portals, generates a out of memory error!!!
i put the limit to 16mb in php.ini , restarted web server and now all runs very well!!!
now i've only a little problem, i can't use any tp theme. Left and right bars appers only if i use the smf default theme.
i thank you for helping me.