System clock is set using bios. When system is booted using smp kernel in Redhat 6, clock is incorrectly read and set to wrong time. Hardware Abit bp6 board. Not using 66 disks, ata video, cdrom(atapi)
This sounds like the system is configured to expect the system clock to be saved in GMT time instead of local time and upon bootup the system date is being set to the time in the BIOS +- the offset of your local time zone. You can check this by looking into the file /etc/sysconfig/clock and see if UTC is set to false or true. If true, then the system does indeed expect the system BIOS clock to be set according the GMT, not local time.