Description:
------------
Unexpected behaviour when SQL queries fail.

Reproduce code:
---------------
<?
    $db_host = "";
    $db_user = "";
    $db_pass = "";
    $db_base = "";

    function error_handler($errno, $errmsg)
    {
        echo $errmsg;
        exit(1);
    }

        // script will hang on sql error
    $dbconn = mssql_connect($db_host, $db_user, $db_pass);
        // refreshes will cause sql server to refuse selection of db
    //$dbconn = mssql_pconnect($db_host, $db_user, $db_pass);
    mssql_select_db($db_base, $dbconn);

    error_reporting(0);
    set_error_handler("error_handler");

    if($_GET['error'] == "plain")
        trigger_error("Error", E_USER_ERROR);   // produce error
    else if($_GET['error'] == "sql")
        mssql_query("SELECT asdf FROM asdf");   // produce sql error
?>


Expected result:
----------------
mssql_connect(): On SQL error the script should not hang but finish.

mssql_pconnect(): On SQL error further connection requests should not fail.

Actual result:
--------------
If an SQL error occurs, database connections established with mssql_pconnect() get lost. New connection requests fail with "mssql_select_db() [function.mssql-select-db]: Unable to select database".

When using mssql_connect() instead of mssql_pconnect(), execution of the resp. PHP script will hang (up to 5 minutes). The error handler will finish its job, but PHP does not close the connection to the browser - it keeps "loading" (although no data is being sent anymore).