Okay I have no idea what you're trying to show us here.  Can you please make this the SIMPLEST sample script you can, and explain it a lot better?  Also do please try to upgrade to PHP 4.2.2

Okay, I have $var in my MySQL Database.
I first eval it so the variable will work.

$var = include("file.php");

that a little easier?

so you have $var in your database, and then you overwrite it by setting it to the return value from the included file?

Where is the bug, this works just fine for me on multiple OSes.  

You may wish to try updating to 4.2.2, if only for the security fixes in it.  

Okay, in my header of my site, I have user the variable $var.

I use fulltext database type, and use the following code so the variable works:

$header = addslashes($myrow[header]);
eval("\$header = \"$header\";");    
$header = stripslashes($header);

I define the $var in variables.php as
$var = include("file.php");

I echo it in my index.php, header.php

The page doesnt load, and then for several hours the server was down. No pages worked

include does not return anything except true/false indicating whether the file could be included.  Your $loginStatus = include and $var = include examples make absolutely no sense.  Could you please write a really short script that causes the crash that we can try on our end?

Okay, I am going to make a full long complete example.

first off, the MySQL Database stores my themes. the theme header is stored in the database and called upon by the var name $header.

I eval it using the code I showed earlier. All variables show just fine. But when I call on $loginStatus I get the problem I described.

Okay I will describe the problem in short:

Header (stored in fulltext mysql database)
(ALL MY HEADER HTML)
<table><tr><td>$loginStatus</tr></td></table>

Variables.php
$path_site = "http://www.w0rms.com";
$loginStatus = include("$path_site/login.php");

themes.php (this converts the themes so the variables are defined)
	 	Connect(); 
		$sql = mysql_query(select from etc); 
		$myrow = mysql_fetch_array($sql);
		$theme_id = $myrow["theme_id"];		
		$header = addslashes($myrow[header]);
                eval("\$header = \"$header\";");    
		$header = stripslashes($header);

Okay, here is index.php The page were all of it comes together:

<?php
// =======================================
// Required Files
// =======================================
require("require/variables.php");
require("require/mysql.php");
require("require/functions.php");
require("require/common.php");
require("require/themes.php");

// =======================================
// We echo the header
// =======================================
echo "$header";

phphphphphphphphp---

?>

That is as deep as I can explain it, without showing the entire scripts; can you create the same error?

No, obviously we can't.  What exactly are you expecting the line:

$loginStatus = include("$path_site/login.php");

to do?  

That line to include a file, since I cant include login.php in my mysql database, I include it by variable..

It might have been include('file.php'); instead, I know it was correct though, I tested it.

That's not how include works.  Like I said before, it only returns a boolean status, it does not return the file.  And what do you mean you know it was correct?  Just look at your code.  Until you can provide us with a reproducable short test case, a gdb backtrace, sensible log messages, or anything we can go on, there is absolutely nothing we can do.
You couldn't even tell us the OS!

apache is OS

include doesnt include the file? As far as I knew require/include worked the same except for the errors.

Look bro, all I know is it totally messed up the server, I explained exactlly how to simulate this, just try it. You will see =)

Apache is not an operating system, it is a web server.

And yes, include does include the file, but it doesn't return it and put it into a variable the way you think it does.

And no, you did not give us a script that we could copy and and run on our own servers to reproduce your problem.