It wasn't too long ago that my computer started loosing time. It was right after I installed the new Microsoft Vista. I'd set the time then shut down the computer after doing some work and upon restarting the computer, I would notice that my computer time had lost two hours. It was getting fustrating because I was use to relying on my computer clock to keep track of time while I was working from home. Finally I was about to give up on adjusting my computer's clock and was headed out the driveway to the shopping mall to purchase a wall clock. I got to talking to my next door neighbor and recieved instructions so back in the door I went and my problem was fixed.
Right click your computer clock and click Adjust Date/Time. When the menu opens up click Change Time Zone and choose your location. For me choose (GMT 05:00) Eastern Time (US & Canada). My computer now keeps reliable time.