Not exactly sure how to reply, however, tech side coming out, can you disable the modem?

There only seems to be 1 other device, that I can think of, other then the pc speaker that can emit "beeps", which is the modem.  Thus, my first recommendation is you disable your modem via the bios (if its onboard), or physically yank it out.

Even if you DO NEED it, try it out to see if that was the problem...might as well narrow it down.