Start with a small sample of data

Also, at line 16, try doing a print "I am now searching using '$item'\n";

If there are blank lines in your @nomi file, you'll get the entire @indirizzi file printed out, because every line in the file will match /^/;

One other note is that you are declaring $line and $item inconsistently. The first $line is never used, since there is a new $line declared for the inner loop.