The script below outputs 25 October twice, and then has
all following days 1 day off. It's fine if you offset the start-time 
by at least an hour.

   $date=909180000;
   echo "<br>$date: ".Date("d/m/Y", $date);
   $date+=3600*24; 
   echo "<br>$date: ".Date("d/m/Y", $date);
   $date+=3600*24; 
   echo "<br>$date: ".Date("d/m/Y", $date);
   $date+=3600*24;
   echo "<br>$date: ".Date("d/m/Y", $date);

Output:

909180000: 24/10/1998
909266400: 25/10/1998
909352800: 25/10/1998
909439200: 26/10/1998 

or, with offset +3600:

909183600: 24/10/1998
909270000: 25/10/1998
909356400: 26/10/1998
909442800: 27/10/1998 

PHP 3.0 final compiled with --with-system-regex --with-mysql --with-pgsql
using Apache 1.2.6; PHP 2.0b12 also used.