Windows 7 - Computer will not sync with an internet time server

I've been having on-again, off-again problems with the clock randomly resetting to a day or two in the future. In the past, going into the internet time settings and telling it to update again fixed it. However the last time or two this has happened, I kept getting a message saying the connection to the server had timed out, and since I was in a hurry, I just reset the date manually and went on my way. The most recent occurrence, I had plenty of time on my hands and decided to see if I could figure out what was up with the internet time sync, and switched it to a different server to see if that would fix it. It didn't, and after a couple tries instead of saying the connection had timed out, it said that "the peer is unreachable". I went through all the default time servers and it did the same thing - it time out several times, and then it said the peer was unreachable. I then went and plugged in servers from this list- same thing. If anyone has any idea what's happening or how to fix it, I would greatly appreciate it. Thanks!

Sounds like you need a new CMOS battery

well that doesn't sound too bad. Is that something I can just go to a computer store and get replaced?

to be honest, I've never had to replace mine. I would assume they would at least be able to tell you where to get it (if they didn't have one on hand)