Whenever I used mc or another ncurses-based program on my Gentoo the output would show strange characters instead of the proper line drawing. Also, the numbers on the numpad didn’t work inside for example nano. The fix is in your default putty settings:
- Window → Translation → Received data assumed to be in which character set: UTF-8
- Window → Translation → Handling of line drawing characters: Use Unicode line drawing code points
- Connection → Data → Terminal-type string: putty
I got this solution from here.