Windows has a feature that allows an application to be ran with a higher level of privilege by running the application as an administrator level user. Due to the User Account Control (UAC) system, draging and droping from and application of a lower user level (typically user level) to and an application running at a higher level.

         

This means that if 4D is being ran as an administrator level, it will not accept items that are being drag and dropped from an application of a lower level.
The only way to avoid this issue is to make sure that all applications that will interact with drag and drop are running on the same level or disabling UAC which will diable security features.