type a php3 file called a1.php3 containing one line
<? Header("Location: /newQS/a/a.php3");?>

telnet to the web server and GET the file:
GET /a1.php3

your telnet response is : Connection closed by
foreign host.

On the other hand,  create a perl .cgi file with the
following line:
#!/usr/local/bin/perl
print "Location: /newQS/a/a.php3\n\n";

now telnet to the webserver and GET it.
you will get the redirected file. 

what causes the different behavior?