Can't load page after updating a node

hello everybody,

i'm having some troubles: when i create a page, i fill the form and then click the submit button.

The page is created BUT the process is not completed because after that i have a blank page without showing any errors, and there are no errors in the log system.

Also, i got the same problem when doing some operation as administrator in the Content management > content page!

This seems not making published any new node...

Thank you for your help.