I don’t want to be too alarmist, but try running the following PHP code on your system:
<?php$date = '2040-02-01';$format = 'l d F Y H:i';$mydate1 = strtotime($date);echo '<p>', date($format, $mydate1), '</p>';?>
With luck, you’ll see “Wednesday 1 February 2040 00:00″ displayed in your browser. If you’re seeing a date in the late 60’s or early 70’s, your PHP application may be at risk from the Y2K38 bug!
Source: SitePoint