In the applications such as blogs, downloads, store and calandar, when I post something I have error EX0
Help me please
EX0 could be anything. You would need to provide more info than that.
What is your IPB version? Is it directly from IPB or nulled? Are you sure your files are not corrupted & are not missing by any chance?
I suggest you to reupload the files, check the permission to see if they are correct or not, and see if your IPB is up to date or not. There were some issues with those apps in past builds of IPB 4.