Description:
------------
I'm experiencing a problem using session_start() simultaneous - ie. in 2
iframes.

An example:
    I have a page with to iframes embedded. Frame 1 runs a script with a
while(true), and at line 1 a session_start().

    A page is loaded into Frame 2, with session_start() as the only content. (Except for <?php and ?> of course)

The page in Frame 2 will not be parsed unless the session_start() is removed
from the top.

It seems as when 2 pages are loaded/loading and executing
session_start() simultaneous, PHP will fail to interpret one of them.

I've tested and determined this issue at two self-contained systems.

===================================
System information:
PHP: 2.4.3
Apache: 1.3.29

Configured with:

'../configure' '--prefix=/usr' '--with-apxs=/usr/bin/apxs' '--with-regex=php' '--with-config-file-path=/etc/php4/apache' '--disable-rpath' '--enable-memory-limit' '--disable-debug' '--with-layout=GNU' '--with-pear=/usr/share/php' '--enable-calendar' '--enable-sysvsem' '--enable-sysvshm' '--enable-track-vars' '--enable-trans-sid' '--enable-bcmath' '--with-bz2' '--enable-ctype' '--with-db4' '--with-iconv' '--enable-exif' '--enable-filepro' '--enable-ftp' '--with-gettext' '--enable-mbstring' '--with-pcre-regex=/usr' '--enable-shmop' '--enable-sockets' '--enable-wddx' '--disable-xml' '--with-expat-dir=/usr' '--enable-yp' '--with-zlib' '--without-pgsql' '--with-kerberos=/usr' '--with-openssl=/usr' '--with-exec-dir=/usr/lib/php4/libexec' '--disable-static' '--with-curl=shared,/usr' '--with-dom=shared,/usr' '--with-dom-xslt=shared,/usr' '--with-dom-exslt=shared,/usr' '--with-zlib-dir=/usr' '--with-gd=shared,/usr' '--enable-gd-native-ttf' '--with-jpeg-dir=shared,/usr' '--with-xpm-dir=shared,/usr/X11R6' '--with-png-dir=shared,/usr' '--with-freetype-dir=shared,/usr' '--with-imap=shared,/usr' '--with-imap-ssl' '--with-ldap=shared,/usr' '--with-mcal=shared,/usr' '--with-mhash=shared,/usr' '--with-mm' '--with-mysql=shared,/usr' '--with-unixODBC=shared,/usr' '--with-recode=shared,/usr' '--enable-xslt=shared' '--with-xslt-sablot=shared,/usr' '--with-snmp=shared' '--enable-ucd-snmp-hack' '--with-sybase-ct=shared,/usr' '--with-ttf=shared,/usr' '--with-t1lib=shared,/usr' 


Reproduce code:
---------------
I've put up an example:

http://home.madd.dk/phptest/

Expected result:
----------------
I've expected frameA to produce desired output "HEST", but it seems like frameA.php fails to be parsed.

Actual result:
--------------
See "Expected result"