If your clock is constantly an hour out, it suggests that it might be set to the wrong time zone. (e.g. one which doesn't auto-correct for daylight saving time). Double-click on the time display to check the settings.
If your computer gradually looses time, it probably means that the CMOS battery (which provides power, when the laptop is switched off, to store the system settings) is failing. It should be replaced as soon as possible, otherwise you'll start encountering repeated CMOS/BIOS errors.
Chris