Couple other ideas to toss your way... your power manager may need resetting, your PRAM battery may be dead, or somehow you may have managed to zap your realtime clock hardware on your motherboard. The only other option after hardware is software, and it's very unlikely that you've somehow managed to whack your OS X -and- your OS 9 clock software at the same time.

You didn't mention what model of mac you have or I'd give you a walkthrough on resetting your PMU and checking your PRAM battery. If you know how to do these things, give it a shot... a PMU reset fixes a world of power and clock related problems.