Since, you're running a win98 system, it suggests you have a dated system. You should really install a new CMOS battery and then check it. Don't take anything for granted. Buy a new battery not some battery laying around. If it still fails, get a clock setting pgm. that uses either NOS(naval) or NTS(national) from Colorado. I use "webtime" from http://www.gregorybraun.com or find a similar one. You can batch mode it to run once on the web or manually.
My office computer (Windows 98) clock has been gaining exactly one hour each week. I work only on Tuesday and Wednesdays and each Tuesday for several weeks it has been ahead by one hour. I reset it each time I see it's off. Then, this Tuesday it was behind by exactly one hour. This problem seemed to start about time of Daylight Saving Time back in March. I don't think it's a battery problem since it is always off by exactly one hour. The computer is shut off when it's not in use. It automatically runs virus scan each Wednesday while I'm at work and since that really slows the whole system down, I don't run any unnecessary programs at that time. Any help would be appreciated.