[TYPO3-english] wizard_add.php wizards return to blank page

[Roland]

hi everybody,

the wizard_add.php wizards in one of my TYPO3 projects have a weird 
behaviour - both in my extensions and in the system extensions (e.g. 
file mounts of backend user records):

after clicking "save and exit" or "exit" you do not return to the last 
record editing session but a blank page is shown as you will be 
redirected to dummy.php from alt_doc.php (303).

i usee TYPO3 4.7.4 - updated to 4.7.5 - but nothing changed. i have 
another TYPO3 4.7.4 project where everything works perfectly.

could this be some server settings problem?

kind regards

roland