This is a still open previously reported bug and isn't fixed with perl v5.12.1:

$ /usr/local/bin/perl -v
This is perl 5, version 12, subversion 1 (v5.12.1) built for x86_64-li
+nux-ld
[download]

$ /usr/local/bin/perl -e '@ARGV = qw(foo);
foo(@ARGV);
sub foo {
    my $x = shift(@ARGV);
    my $y = shift;
}'
panic: attempt to copy freed scalar 13280e0 to 133a630 at -e line 5.
[download]

I don't have a 5.13 handy to test with and it's too late to build one :(

update:

Of course, it could be an entirely different problem. It would be helpful if you could provide a minimal example of your program that exhibits the same panic.