The first thing to do is to try "disabling" PHP 5 with the button, and then re-enabling it. Sometimes that will clear it up. Your
.htaccess should show something like
AddHandler application/x-httpd-php5 .php5 .php4 .php .php3 .php2 .phtml
AddType application/x-httpd-php5 .php5 .php4 .php .php3 .php2 .phtml
after you enable PHP 5 -- did it get updated? Your
.htaccess is 644 permissions (not 444)? There are no other handlers in your
.htaccess defined to handle PHP files?
If all this fails to get PHP 5 working (according to phpinfo), open a support ticket.