Hi there

Did some Google search , i found a final fix for Ettercap and resolved the crashing/freezing problem.
1) Uninstall the existent version of Ettercap on BT5 using package manager.
2) download these packages:

https://launchpad.net/~timothy-redae...izzt1_i386.deb

https://launchpad.net/~timothy-redae...izzt1_i386.deb

Now you can call Ettercap from menu or terminal, it wont crash or freeze specially during host scan.

Good luck
GD