The MSSQL extension seems to have a few issues under heavy stress. Running a similar test with a mysql server produces no errors:

<?
$link = mssql_connect("127.0.0.1","1","1");
mssql_select_db("test");
$bit_result = mssql_query('SELECT testbitmoo FROM testbit');
$bit_row = mssql_fetch_array($bit_result);
print $bit_row['testbitmoo'];
mssql_close ($link);
?>

Running the above test script produces the following error log entries:
1. MS SQL:  Unable to connect to server:  127.0.0.1 
--> mysql doesn't fail taking new connections, but that error could be a server config setting.

2.
Corrupt Log file Entries e.g. : 

ndex.php on line 3
2
ine 8
tdocs\php\index.php on line 8


3. Failure connecting to server "null":
MS SQL:  Unable to connect to server:  (null)
(should be 127.0.0.1)

4. Attempting to connect as a null user:
MS SQL message:  Login failed for user '(null)'.
(should be "1")
Paul