OS X 10.11 El Capitan - Verifying file dialog, every time a file is opened Not sure, if this question will be closed, but the situation is quite annoying.

Every time, I open some .pdf or .jpg file, a dialog appears,and it seems to be stuck there for a long time. After I click on close button, and open the file again, it opens without the dialog.
The cause might be that the file/folder was downloaded.

In any case, you can remove the 'quarantine' status with

xattr -d com.apple.quarantine "/path/to/Geometry.pdf"

you can add the -r flag to make it recursive, in case you still have trouble.