First guess: 

        $master_letter_list = lc $1; ## Force all letter lists to LOWE
+R CASE only
        %master_letter_freq = ();  # <--- ** MISSING LINE **
        for (split //,$master_letter_list)

[download]

Every time $master_letter_list is changed, the frequency hash must be cleared before being added to.

The occasional "failure" is due to the differing sequences of user interaction.

In reply to Re^3: Next from inner loop only works "most of the time" by tybalt89
in thread Next from inner loop only works "most of the time" by Marshall

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