I'm having an issue with VirtualBox with 17.04. I did not have this issue with 16.10. When ever I try to attach an ISO of a CD/DVD the VirtualBox application immediately closes. I was able to get around this by using the cli tool VBoxManage. In my case I was trying to setup a simple Windows 7 x64 VM.
Code:
VBoxManage storageattach "vmname" --storagectl SATA --port 1 --device 0 --type dvddrive --medium "/mnt/drive/some.iso"