I had that annoying noise on my VR Calias and it almost drove me mad. I tried checking the handbreak switch and stuffed around with it for weeks. One day I banged the dashboard and found it stopped. It turned out to be a loose globe in the dashboard. I replaced it and had no trouble afterwards. Hope this helps.
AFAIK there are only 3 beeps you'll get out of the VS (unless something is VERY wrong) they would be speed alert (check it is disabled) low fuel warning (check for light on dash and fuel gauge function) or handbrake on, which only occurs if you start moving while handbrake is still on. If light is on dash when handbrake is off, then the switch is probably faulty. It is located at the rear base of the handbrake.
EDIT: *w00t* 600th post
2nd EDIT: VS does not have seatbelt sensors. It does, however, light up a seatbelt light on dash for 5 seconds when you turn the ignition on to "remind" you.