This can occur if any settings in the bios have been changed - the system will reboot a few seconds after initial power up. You can try changing the bios settings to default, save and exit. See if this resolves the issue. Also you can try clearing cmos settings by removing battery (or removing jumper on some boards - check your manual). Then replace battery/jumper, power up - enter bios - enter new time and date - save settings and exit.