LoL however.. I got it in this way. I think the problem was the first foreach loop..

    
else {  
                    $line2 =~ s/$word/$correct[$user]/;  
                    $word = $error;  
                    @words = grep { $_ ne $error } @words;  
                }
[download]

I made a substitution in line, then I copied $word in another scalar, $error, and then I created again the @words array without $error !