while (1) {
    my $loop_start = time;
    
    #.... code

    my $sleep_time = 86400 - (time - $loop_start);
    sleep ($sleep_time);
}
[download]

I suppose if that were the case you could adjust the
sleep time back one hour (i.e) 60*60*23 instead of 60*60*24
to account for the hour it takes the program
to run. Just a guess off the top of my head...
-LordAvatar