See http://www.faqs.org/docs/Linux-mini/Visual-Bell.html|this tutorial]] for how to disable the visual bell on your system. Like my co-workers maybe yours will congratulate you as well :)
I especially like this part:
Speakerectomy is by far the most brilliant solution to the audible bell problem. As its name implies, it consists in removing the beeps by removing the beeper. The operation is straightforward and you don't even need any anesthetic, but if you want there's room for refinement.
It goes on to tell you to use the "Slow down"-button found on older PCs to enable/disable the speaker.