I don't know what that "Drag & Drop" extension is. It's not on my system anywhere, maybe it's a third party thing. It not being active is probably not the problem.
You might want to go into Extensions Manager and select the "9.x Base" or the "9.x All" set, and then do a restart while holding down command (apple)+ option--this will rebuild your desktop. Then give it a try before activating other extensions, especially third parties.
What OS are you running? That info could offer some clues.