System:
Linux
PHP 4.06
Apache 1.3.19
mySQL 3.23.38

side1.php
  session_start();
  session_register("var1");
  Header("location:page2.php);
 
side2.php
  session_start();
  session_is_register("logon") returns false;

I check the mySQL logs (i have a personal written session_handler, which works fine under a lot of different systems with mySQL) and see following problem

side1.php: SELECT * FROM Session WHERE SessionID ...
.... script queries from side1.php
side2.php: SELECT * FROM Session WHERE SessionID ...
side1.php: UPDATE Session SET ... WHERE SessionID ...
.... script queries from side2.php
side2.php: UPDATE Session Set ... WHERE SessionID ....

instead of the normal: 

side1.php: SELECT * FROM Session WHERE SessionID ...
.... script queries from side1.php
side1.php: UPDATE Session SET ... WHERE SessionID ...
side2.php: SELECT * FROM Session WHERE SessionID ...
.... script queries from side2.php
side2.php: UPDATE Session Set ... WHERE SessionID ....

i think the problem is that the header("Location: ...") works so fast over the intranet network, that my old developer machine isn't fast enaugh to handle the script SQL statement, before the new site request reach another process of the apache and query the session table.
the problem is that the buffer is flushed before the session related operations are done

What can i do against this behavior?
thanx