Since 01/01/2000 :

[root@angelus /root]# cat /etc/sysconfig/clock
UTC=false
ARC=false
[root@angelus /root]# setclock
mktime() failed unexpectedly (rc -1).  Aborting.
[root@angelus /root]# date
Mon Jan  3 09:31:38 CET 2000
[root@angelus /root]# rpm -qf /usr/sbin/setclock
timeconfig-2.5-1

After a reboot, the problem disappears :

[root@angelus /root]# date
Mon Jan  3 10:40:57 CET 2000
[root@angelus /root]# setclock
[root@angelus /root]#