in the Connections/PowerStoreConnection.php file try changing line 9:
$PowerStoreConnection = mysql_pconnect($hostname_PowerStoreConnection, $username_PowerStoreConnection, $password_PowerStoreConnection) or trigger_error(mysql_error(),E_USER_ERROR);
to:
$PowerStoreConnection = mysql_connect($hostname_PowerStoreConnection, $username_PowerStoreConnection, $password_PowerStoreConnection) or trigger_error(mysql_error(),E_USER_ERROR);
basically change:
mysql_pconnect
to:
mysql_connect
if you continue to have a problem, i'll need to troubleshoot the site directly, in a private message, include a link to the Power Store admin, admin login and FTP details so i can reproduce and troubleshoot the issue.