A continuous beeping alarm after you've had the computer on for a while very often indicates that your CPU is overheating. Download EVEREST or some other diagnostic tool to check the temperature of your CPU and the rpm of the fan that is supposed to be cooling it (maybe it's broken?).
Unless you mean the beeping sounds occur during startup after it crashed and you've restarted it. In that case you should look up the exact beep codes of your BIOS to find out what it means.
http://en.wikipedia.org/wiki/Power-on_self-test