Deny Dropbox from running with GPO
Start Group Policy Management Editor
Computer Configuration\Policies\Windows Settings\Security Settings\Software Restriction Policies
If you see:
On the right screen, then you need to right click on Software Restriction Policies, and choice “New Software Restricition Policies” first.
Right click on
Additional Rules, and choice “New Path Rule…”
Make a another new Path rule, and set path to:
Set security level to Disallowed
This will update the group policy on the machine this command is run at.