Check services versions, directories rights, groups definitions etc.
Put the file checklampconf.php in the root directory of your hosted space. Add exe right :
$ chmod +x checklampconf.php
$ ./checklampconf.php
Adjust some vars according your needs, for example :
$processing -> params["apache"]["version"] = "2.2" ;
$processing -> params["apache"]["modules"] = array("php5|suphp","rewrite","expires");
$processing -> params["php"]["version"] = "5.3" ;