product creation / editing does not work = Error 500

[wasserfall_deluxe]

Hello, I've just installed the brand new package VEYTON 4 Community Edition. Everything works fine exepting creating new products. Clicking on new product an empty page results. Obviously the new data set is created without inputs but its not possible to edit those data afterwards - same result.

From ext-js there is an AJAX call:
http://www.domain.de/xtAdmin/adminHa...roductgridForm
which results an error 500 - all error logs (server, vhost, veyton) are empty.

Tested in different browsers: Chrome, Firefox and Safari on MAC

PHP Version 5.2.4

Please, can somebody help me? // Auch gern auf deutsch
Thanks!

[wasserfall_deluxe]

memory_limit auf 64M und alles ist gut!!!