#!/usr/bin/perl -w
use strict;
use Bio::SeqIO;

my $file = $ARGV[0];
open INFILE, "<$file" or die "$0:  Can't open file $file: $!";

for (my $trial = 1; $trial <=2; $trial++)
{
   seek(INFILE,0,0); #This is line 10
   print "Trial $trial\n";

   my $i =1;
   my $in = Bio::SeqIO->new(-format => 'fasta', -fh => \*INFILE);

   while( my $seq = $in->next_seq  ) {
      print $i++, " : ", $seq->seq(), "\n";
   }

}

##</code><code>##

Trial 1
1 : TGCAATCACTAGCAAGCTCTCGCTGCCGTCACTAGCCTGTGG
2 : GGGGCTAGGGTTAGTTCTGGANNNNNNNNNNNNNNNNNNNNN
seek() on closed filehandle INFILE at test.pl line 10.
Trial 2
readline() on closed filehandle INFILE at /usr/lib/perl5/site_perl/5.8.0/Bio/Root/IO.pm line 440.