MS Access 2000

I had a Access 2000 db located on one NT server. In recent months, an error occurs time and again, and is very annoying. Though I can fix it every time, I’d like to know why and how to fix it once for all.
The db server has about 12 users accessing to the same database.
I have a form with a lot of buttons. When I click one button, it will prompt me a dialog box for entering a customer id. If the customer id is found, it will produce a report about the customer. However, this button does not always work. Sometimes just nothing happens when clicking. If I go to “Tools | Compact/Repaire database”, then that button will work again. I just wonder how this can happen and how to fix it.