Adding the necessary bits to make your sample run the error relates to how you generate @taulell and what then happens to it. Here is some sample code that reproduces the problem and also demonstrates what is happening.

use Data::Dumper;

# everything is fine using this @taulell array
#@taulell = ( ['B1','B2','B3'], ['B4','B5','Y1'] );

# here is how you set @taulell
sub inicialitzacions
{
    $torn='B';
    @{$taulell[3]}[3,4]=qw(B N);
    @{$taulell[4]}[3,4]=qw(N B);
    @pos{'x','y'}=(2,2);
}
inicialitzacions();

# @taulell looks like this
print Dumper(\@taulell);

my $num=0;

for(@taulell)
{
    $num+=grep /B/,@$_;
} 

# @taulell now looks like this
print Dumper(\@taulell);

addstr(2,1,"B = $num");
addstr(24,3, "Y = $pos{y}");
$num=0;

map 
{
    $num+=grep /B/,@$_;
} @taulell;      
addstr(3,1,"N = $num");
addstr(24,35,"Tecla = <$key> ");

# @taulell now looks like this
print Dumper(\@taulell);

sub addstr {}
[download]

What you can see is that first loop modifies your data structure (into an array of arrays) which allows your map to run. When you kill the first loop you pass map your 'really weird' data structure and the map chokes

cheers

tachyon

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