On 64 bit and 32 bit ubuntu ascii versions hitting 'w5', 'w.', 'ws' or 'w?' enters into loop spamming "Unknown command: 'ÿ'." extremely rapidly (something like 20000 times per second on my system). The game still responds to other input normally, though commands requiring multiple keypresses, like ':m' must be entered by pasting the command.
On 64 bit ubuntu noteye version and on windows version (running with wine) w5 seemed to work properly.
On dos version (running with dosbox) w5 starts waiting for input but will not spend a single turn.

Some other walk commands did not cause any problems, at least 'w<', 'w*', 'wm' or 'wi' seemed to work fine.