don't really know how to fixs this, googled a lot and searched in the forums but no answer was good for this strange behaviour:
I do not have REVISIONS metabox and NO DISPLAY SETTING OPTION to switch on the revision metabox.
this happens just in pages editing screen, in post's I have it normally.
- tried to deactivate all plugins
- tried to switch to default template (twenty twelve)
- tried to overwrite via ftp wp-includes and wp-admin
- searched the whole wp directory for 'WP_POST_REVISIONS' to find any FALSE definition of it
still not working on any browser