Test this code if you will:

// Start- Copy and Save this code as phpbug21674.php in a path folder name "site3"
<?
// PHP BUG# 21674
// This script must be saved to Docs root path of virtual domain-A

// To debug.. change the path to the path on your test server
require_once ("/home/sites/site2/config.php");

echo "Hello - Testing PHP 4.3.0 bug# 21674<br>";
?>
// End - Copy and Save this code as phpbug21674.php

// Begin - Copy and Save this code as config.php in a path folder name "site2"

<? 
include ('extras.php');

?>
// End - Copy and Save this code as config.php


// Begin - Copy and Save this code as extras.php in a path folder name "site2"

<?
// -- field definitions --

$extra=array();   // leave this line alone

$extra[info1][name]="Alias Name/Nickname";
$extra[info1][type]="text";

$extra[info2][name]="Your Gender";
$extra[info2][type]=array("Female","Male",);

$extra[info3][name]="Relationship Status";
$extra[info3][type]=array("Single","Single-Looking for Couples","Couple-Looking for Singles","Dating","Involved/Partner","Involved-Seeking New Friends","Married","Married-Seeking Discreet Friend","Engaged","Divorced","Widowed","Player","Just looking for friend","Just Looking for Sex Partner","Undecided");

$extra[info4][name]="Sexual Orientation";
$extra[info4][type]=array("Heterosexual","Gay","Lesbian","BiSexual","BiCurious","Rather Not Say");


// do not edit past this line

$extras = array();
for ($i=0; $i < 21; $i++)
 { $marker = "info".$i; // print $marker."<br>"; // debug
 if (strlen($extra[$marker][name]) > 1)

  $extras[]=$marker;
 }


// in general, to display extra variable values, use $extra[infox][value]

?>


Now execute php21674.php to reproduce errors.

It works fine here...
Is your include_path still '' ?
You *must* have '.' in your include path for relative includes to work; have you tried that?

This is what my phpinfo() says

include_path         .:/usr/lib/php

add:
var_dump(ini_get('include_path'));
to the line before the require_once in the phpbug21674.php script and paste the output here.

Here are the results to your request.

string(14) ".:/usr/lib/php" 
Warning: main(lang.php) [function.main]: failed to create stream: No such file or directory in /home/sites/site2/web/IV/config.php on line 97

Warning: main() [function.main]: Failed opening 'lang.php' for inclusion (include_path='') in /home/sites/site2/web/IV/config.php on line 97

Warning: main(extras.php) [function.main]: failed to create stream: No such file or directory in /home/sites/site2/web/IV/config.php on line 98

Warning: main() [function.main]: Failed opening 'extras.php' for inclusion (include_path='') in /home/sites/site2/web/IV/config.php on line 98
Hello - Testing PHP 4.3.0 bug# 21674// End - Copy and Save this code as phpbug21674.php

Can you do the same for the config.php file.
(and look to see if you have some .htaccess file in there too that might be changing PHP settings)

OK. At your request, here are my results.

string(14) ".:/usr/lib/php" string(14) ".:/usr/lib/php" 
Warning: main(lang.php) [function.main]: failed to create stream: No such file or directory in /home/sites/site2/web/IV/config.php on line 97

Warning: main() [function.main]: Failed opening 'lang.php' for inclusion (include_path='') in /home/sites/site2/web/IV/config.php on line 97

Warning: main(extras.php) [function.main]: failed to create stream: No such file or directory in /home/sites/site2/web/IV/config.php on line 98

Warning: main() [function.main]: Failed opening 'extras.php' for inclusion (include_path='') in /home/sites/site2/web/IV/config.php on line 98
Hello - Testing PHP 4.3.0 bug# 21674// End - Copy and Save this code as phpbug21674.php

and can you confirm that the var_dump(ini_get('include_path')) is on the line immediately above the include that fails?

I'm asking because the line numbers in the report don't seem to have changed, and I would have expected them to at least have increased by 1.

You did not ask me to place above line that include fails. You asked me to place above require_once in the config.php file. That I can confirm.

Just to be extra sure:

in config.php, do lines 97 and 98 look like this:

var_dump(ini_get('include_path'));
include ('extras.php');

If not, please make sure they do and report back.
If they do, then something really strange is going on.

Hello Wez:

Not it does not look like that.  I was asked to include var_dump(ini_get('include_path'));

before the require_once statement in the primary script, phpbug21674.php

Remember there are two scripts located in different paths representing two different virtual domains.

/home/site3/phpbug21674.php (contains a require_once ("/home/sites/site2/web/IV/config.php");

and /home/sites/site2/web/IV/config.php" ---> contains
include_once ('lang.php');
include ('extras.php'); 

However, I did go back and also added the var_dump to config.php to reflect as follows:

var_dump(ini_get('include_path'));
include_once ('lang.php');
include ('extras.php'); 


Results: Same results = Failed to create stream:

Again, this script worked fine on PHP 4.1.2 Now it seems to get it to work, I have to reference the absolute path.

The point of asking for var_dump(ini_get('include_path')); is so you'll show the output of it.  This is a form of debugging.

The problem has to do with the include_path directive.  Now we're trying to figure out why/where it gets set to '' before doing some of these includes as this seems to be the case.

So, whenever you get this error:

Warning: main() [function.main]: Failed opening 'foo.php'...

Add this line above the include:

var_dump(array(ini_get('include_path'),__LINE__,__FILE));

This way we'll know some useful information.  Basically put this line above EVERY one of these failed includes, such as the inclusion config.php, extra.php, and lang.php.  

Please do this and show the output in your next reply.  Btw, I modified Wez's debug dump a little so we can be a little more specific :)  Also, be 100% sure you are not setting this directive in either httpd.conf or .htaccess.

This bug has been fixed in CVS.

In case this was a PHP problem, snapshots of the sources are packaged
every three hours; this change will be in the next snapshot. You can
grab the snapshot at http://snaps.php.net/.
 
In case this was a documentation problem, the fix will show up soon at
http://www.php.net/manual/.

In case this was a PHP.net website problem, the change will show
up on the PHP.net site and on the mirror sites in short time.
 
Thank you for the report, and for helping us make PHP better.