In php strtotime doesn't work for euro date formats d/m/Y
m/d/Y and d/m/Y are completely ambiguous for dates like 1/12/2008, 12/1/2008, etc.
You need to know the format you're working with and use something like:
$a = explode("/", $d);
$ts = mktime(0,0,0,$a,$a,$a);