My clock on my notebook does nt work

Question

I cannot find the way to fix the clock on my Windows Vista. It does not show the proper time and it is always behind the actual time. I need to adjust it manually at least three times a day. How could it be fixed, so it will not be so annoying?Example is if i set the time to say 1200 the next day will still show 1205.or even afther a week still show 1205 untill i set it again. I ahave restore amy system but still the sameOperating System: Windows Vista.I have read all these article but none of them seems to provide solutions,