file upload problems using php3&php4 as conccurent apache modules

i upgraded to php4 but to be able to use my old php3 scripts without editing them all i also installed php3. the both modules are compiled with the enable-versioning flag and running fine. only when i use <form action="xyz.php3" method="post" enctype="multipart/form-data"> in a script to upload files and return the values to the same script it hangs. i'm able to see the uploaded files in my /tmp directory. whats wrong? thxs Michael