sound of clock at each hour

[xiaowei]

Recently we found our windows XP workstation, at each
whole hour we can hear the sound of clock on the computer.
I cannot figure out where it comes from.

It's really annoying, how can I turn it off, but I don't
want to turn the speaker off, for we do use it for some
alarmed task.

I use auto download signature file feature in anti-virus
software etrust-inoculate, I set up run every 4 hours a
day, I wonder if it comes from there, but how can it
sound each hour?

Any ideas would be appreciated

 

[xiaowei]

Never mind. It comes from Taskplus ddfault settings